Locked the contract. 30 days expired and they made an excuse to extend the contract.

To what extend?

As a listing agent, I explain to seller that an inspection can be more protection for them, anyway, because 1) buyer waives right to repair anything discovered in the inspection if not negotiated during inspection period, so fewer surprises at final Walk Through, and 2) buyer less likely to succeed in blaming seller later for something even their own professional didn’t find (unless seller was really hiding it).

However, your credit could also be impacted if you're co-signing or jointly applying for the loan.Regarding the funds, lenders usually require that the down payment funds be seasoned, meaning they need to be in the account for a certain period, often 2-3 months, to ensure they are not borrowed.

However, bonus depreciation doesn't apply abroad; instead, the Alternative Depreciation System (ADS) with longer periods is used.The Short- Term Rental Loophole Explained (biggerpockets.com)

There is no grace period for correcting existing contracts.

LTR is more plausible but often HOA requires primary residence for a period of time before renting it.  

Use dynamic pricing software in conjunction to you checking manually daily/near daily.3 - Discounting slow period and longer stays.

Until I wait for the seasoning period to be over.

Bonus depreciation will decrease to 40% next year, but we are hopeful to see the bill passed to extend the 100% bonus deprecation in the future.