The best moment to buy in would: a decision is done- either somebody won or was out; if a Hardway is being done at the far end of the layout, and when the game's dice are at the

middle.
If you are coming in to join the game, avoid squeezing right in front of the active shooter, I've seen more than
a few shouting matches happen because of this kind of thing. If it's primetime for the casino, meaning it's peak hours for them as far as human traffic is concerned, lessen up on the prop bets. I mean, it is your right to bet what your heart desires, but have you realized this? Prop bets take up so much time, more than once, I've experienced being in a game where others do prop bets which cut down the number of rolls to 60/hour, and that's BORING. If you have to know, 100 to 110 would be within the norm.
Another thing, you need not be best friends
with the dealer, but being pleasant enough (you can be sociable even if you are a loner, that takes maturity) with him/her would pay dividends. Two things that would happen if you are in good terms with the game's dealer, one- you'll have more fun. Two, the heat would not be for you, and when I say heat, I am not referring to the temperature of the room. (Hey guys, you know what heat is, in casino parlance huh?)