I'd go by the "defining the relationship" conversation. Assuming that these are not the same date, do you go by the first day you met, first Luckily for my various partners, I'm not particularly fussed about celebrating it on any particular day.
We cover healthy relationships, what's the right age for a boyfriend, sexual feelings, and more. Do I know what I'm ready for in terms of physical stuff? Usually, though, it means doing something sexual with somebody you're not dating.