Hi Doctor, I Just Finished My Last Month Pill Pack

Hi Doctor, I just finished my last month pill pack of lo loestrin fe and have started on sprintec. We do not use any back-up method but are still trying to avoid pregnancy. How long do we have to abstain from intercourse until the new pills take effect? I was told one week to be on the new pills is fine, but want to confirm if this is accurate.

Also, last month I missed a pill in the second week and did not "double-up" until about a week later. Does this make a difference in answering this question (my doctor said it might but I was confused). So, I guess the question is, do we have to abstain more than 1 week?