You are supposed to wait 6 - 8 weeks to do any sexual activity that involves exchanging body fluids... *shrugs* me, I waited three weeks, lol. I just can't stay away from my hubby's cock that long. *grins* I used antiseptic mouthwash afterwards, and I didn't let him cum in my mouth.
As for whether or not girls like it... I know I do (I'm bi). And I know my hubby does, too, lol.... As with anything, the tongue ring isn't all there is to good cunnilingus, patience, care and concentration are necessary, too, lol.
Good luck... Just for the record, I LOVE having my tongue pierced. I'm so glad I had it done.
Bryn