@Sarah Cowns Welcome to BP and congrats on taking your first step! Even just putting your goals and concerns in writing is still a step, so well done.
As for your situation and questions, there are a few things to consider before anyone gives you 'first step' advice. Ok I tend to ramble on BP, so I will try to keep this concise (but, seriously, lol).
1) You have debt, but you've already made a smart move by getting it onto a 0% interest card (amazing how many folks don't know how to take advantage of that, well done there as well). How long is the term? When do you need to have this paid off by, and under your current circumstances can you hit that goal?
2) If you can easily hit that goal with your current income and have some income left over, then start saving for a downpayment. If paying this off before the 0% period is over is going to be a struggle, for any reason, I'll be the conservative investment advisor here and say just pay that sucker off asap and put off investing until it's done. I pretty much always advise getting rid of credit card debt before investing, the only reason you have wiggle room is because it's already at 0%.
3) One thing to consider (though don't take this as a gospel recommendation) is that you could continue to move that debt around onto another balance transfer card when this period is up IF IF IF IF you can do so with no fees. Again, I very much recommend that you try to bust through this debt asap, but if you think that will be a struggle for any reason (and again I think investing should be the secondary priority here), at least come up with a plan for what you will do if you can't kill that debt before your current 0% period elapses. Two solid cards for this are the Citi Simplicity and the Chase Slate, but of course, check on terms and conditions etc before you pull any triggers. I have a friend that is very credit card savvy (travel hacking etc) so these are recs that I've heard from her and I know have been used successfully by many folks in those circles. Always do your own research, the point here is that you need a plan for this debt if you can't kill it before the 0% period is over.
4) So your debt is one thing you need to tackle, of course. I'd say that you should use the time you have while you do that to do some more thinking about what kind of REI you want to get into. You've said rentals, does that mean you want to find properties, analyze deals, handle rehab, find tenants, and then manage them? Or do you want to build a team (agent, contractor, PM) that does those things, and you manage that team? Do you have the time and energy or skillset to do those things? Do you want to be a landlord? There are a lot of ways to do real estate investing, but they aren't all right for every person or every lifestyle. You need to be very specific about your needs and goals with regard to time, energy, budget, and control. Hone in your expectations and requirements and you'll help yourself avoid long-term headache.
5) Re: your timeline. The end of the years is well and truly nigh, so I would advise you to maybe back off on that. It is 100% understandable that now that you and your husband are on the same page, you're both itching to get started. Everyone's been there. But don't pull the trigger on something just so you feel like you've 'done' something. Taking the time to really strategize and clarify your goals and needs is going to be worth the potential few months of lost income. Plus, you can pay off your debt in the interim.
It sounds like you may be psyching yourself out a bit, but at the same time, very few people have been happy having jumped into something they didn't understand just because they felt like they shouldn't wait any longer. Yes, the advice is always to 'just take the first step', but what those people mean is that, once you know the basics of how to analyze a deal and know exactly what kind of investment you want, don't get mired in analysis paralysis waiting for the absolute perfect deal. If you're not yet to the point where you can confidently run numbers to assess a potential investment, don't understand ROI or equity or how to estimate expenses, you're not ready for that so-called 'first step'. When people get successful enough to start running seminars, it's easy for them to gloss over this part of the process and just say 'read everything, then jump in'. There's a lot of homework that goes into successful REI, so don't cheat yourself out of a solid foundation because someone who's already millionaire dared you to.
Oh and, re: seminars, I personally don't think folks should waste a ton of money on things like that. REI meet ups in your area or free webinars, heck yes, learn all you can! But don't spend $$$ to have someone tell you what you can learn here. You're a nurse, so I'm guessing you've got the brain to figure this stuff out on your own if given the time and resources. Luckily, you have both.
You're not yet at a point in your REI journey where you'll be using 'systems' or 'lead generators', you're still learning the basics. You can learn that here, and you'll find most folks on BP are extremely helpful and won't make you pay $1000 for the privilege of listening to them talk ;) That money could be put to better use paying off debt, and then building your downpayment savings.
You maybe don't have a leg up the way some folks do when they start REI, but you aren't in a bad position, just a transitional one. Take the time to get that solid foundation. Pay off your debt. Solidify your goals. Ask questions. You'll be glad you took the time to do it right.
Good luck!
Clayton