This is how i took this topic:
I'm bi-married(maybe i'm in the closet, but that's a far deeper story) and i have only one 'buddy', who is married as well. He says he's hiv- and he was upfront saying a few months back he had done oral on a guy who he thought was promiscious, but he did not let that guy cum in his mouth. (i'm sure precum got in, but that was it)
I recently had 3 teeth pulled, 2 of those being wisdom, and the week after i had dry socket(major pain). After a couple weeks, the dentist told me all teeth/gums were healed. Now i did'nt ask her 'how long before i can give head?'..lol, as that's a bit embarrasing, as she knows i'm married.
And while i was oh so tempted to meet up with my buddy 2 weeks after it was healed, i decided that i'd wait almost 4 weeks(25 days to be exact).
And yes, i did oral on him(and him on me..lol, it's a 2 way street afterall), and he did not cum in my mouth, as only some precum got inside my mouth.
I did not use Listerine up to this point, as i only use warm water with salt mixed in.
Now it was rough to hold off for those 25 days after healing, but i had to think, what was the timeframe i need to do so, so i have no regrets? And i figured i need to wait at least 21 days, for my piece of mind.
I'm pananoid about catching hiv, and while i would of liked to hold off for say 30 or more days, i felt content with the 25 days, which was probably way too cautious, anyway. (and i had no sex for 6 weeks, so it was not easy to wait. And I don't have sex with my wife)
Now, i'm sure it's about 14 days or so that you need to be cautious, before doing oral once again. But that's something you may wish to think to yourself before doing so, as far as how long is enough, for your peice of mind?
Good luck to you guys, please always think with your big head, before your little head gets you into trouble, ok?