Lease-backs are only good if everything goes exactly to plan. There are some pretty major risks involved, primarily to the buyer of your house. The compromise is that with the leaseback, the buyer pool will be smaller due to many people not wanting to take the risk or wait that long, meaning lower effective price usually. You could also open yourself up to eviction if you don’t find a new home and stay past the lease period, which isn’t entirely impossible in the current market.

My recommendation is to make it so that the two transactions are not depending on each other. That is, buy the new house without having to sell the old one. Then sell the old house once moved out and if necessary refinance the new loan if you like.

If that’s impossible, then it’s mainly about balancing risk and that is highly dependent on your goals and timeline. The longer the contract the more likely something is going to go sideways. Getting your current house sold isn’t the problem, finding the next one is. So that is the primary focus at this point. The rest of the details and timing are very much on a case-by-case basis.

5 bedrooms for 450k close to USF is going to be extraordinarily difficult. For one, 5 bedroom homes are pretty rare. Would be easier to find a 4 bedroom with some nook or feature that would be usable for the purpose you wanted or subdividing a 4 bedroom into 5 at this price point. 5 bedrooms are more in the at least 500k range nowadays.