Assuming you aren't a cash buyer, six months is the standard wait. Most first-timers can't turn a property around that fast anyways (in spite of their rosy projections), so it's typically a non-issue.
I don't think there is a standard across all lenders, but it's usually six months. You can probably find a lender with no waiting period at all as well, though.
@Elizabeth Tiburcio - Typically 6 months is the norm for conventional refi's. The alternative to that is you could reach out to some of your smaller local banks and one of them may be able to refi faster than the 6 month time frame.