If they happened before, ask the lender who preapproved you, what affect they will have.
(Please note: when you choose an answer as a Best Answer, or at least give a thumbs up, it helps those who answer questions here.)
Best of luck.
I don't think that's gonna damage your situation as much as you think. Overdrafts can be corrected and fixed and your loan (if credit & finances are in order) should be approved by the right lender.
Best Of Luck