Mortgage and Insurance

Until last month my FICO score was 771, but then two things happened.  In late November I accepted a $2500.00 line of credit increase and then I got very near to the max limit on my other card.  Subsequently, my FICO score dropped to 743.  I use my credit card for everything, but I pay it off every month and the total amount of interest that I paid last year was only $7.00.  I have since learned to not use my credit card so liberally, even though I pay it off every month.  So, my question is as follows:  If I keep my credit utilization under 7% and do not accept any increases in my credit limit or open any new accounts…just how long will it take my score to get bumped back up?  I want to purchase a new house this summer and I want to get the best mortgage rate.  I thank you all in advance for any comments that you might have.