Sex right after AF?

Hello everyone! I was wondering, are there any benefits, or drawbacks to having sex right after AF, like the last day where there is just spotting? I mean, I know I'm not ovulating at that time, but does it do any harm to have sex at that time (with regards to TTC)? Also, on the day of spotting with very little flow, is that technically your last day of your period, or is it the day before, where there is an actual flow still? Thanks!