One thing you can do is get a copy of your credit reports now (annualcreditreport.com is free if you haven't used it in a year). You should be able to see how often those creditors update your record. It's probably monthly.
The lenders decide your credit score, not the credit bureaus. If the creditors you paid off update records monthly, you can wait two months to be safe, and you should have a nice clean record when you approach the lender.