Question about lender pull and interest rates

[tsever01]

So I have worked hard to clean up my credit report over the past several months so that I could purchase a house.  My EQ score is now 681 and the TU that I pulled from this site is 675 (I know that it is likely not accurate) so I think I am ready for prequal.    I could probably sqeeze several more points out by paying down one of my credit cards and I am still trying to GW a charge off.  My question is this.  If I have the broker pull my credit now for prequal will the score that the pull be the score they use when determining interest rates or will they pull again?  I am trying to decide whether or not to wait and get my scores as high as possible or should I just go for it?

[LondonMassey]

depends which loan you're going for. Also, home prices and interest rates are going up, at least where I live, Las Vegas. So I'm happy to be under contract now and should have a 4% rate at close. It's a shortsale, so who knows in this market.

[tsever01]

I am trying to get into a USDA Guaranteed loan.  House prices in my area are pretty much at a standstill it seems.