HELP! New investor, great deal, existing tenant paying low rent
So I'm working on my first deal as an investor. It's a condo that's got a tenant paying $400 under market until the end of November 2022. It's a condo that will net me $700 monthly after all expenses. Seller has given me all of the scoop, and his bottom line. I'll be the first view it and if good will make a cash offer. The tenant is long term and they want to stay and tried finding someone or trying to buy it with no luck. My worry is that I will run into a problem when I raise the rent. Even if I keep it $100 under market, I'm sure they'll choke. Not sure ofntheir situation, age, etc., but should I be scared of this deal/could it present problems?
it's 35% current market, needs nothing but paint and maybe flooring. 2br 2ba 1000 Sq feet.
Thanks in advance