Quite simple. Wait ** years until the load roar turns into being the "norm" :P (12-15 sounds about right ;P)
Honestly, though, the real answer is whenever you are able hehehehe
Kid passes out? Quietly play. Kid wakes up? AFK break until kid goes back to sleep.
Get the kid interested in playing. "Hey look at this, doesn't it look cool/pretty?" "Want to try running my character around?" (take to safe-ish area and let them explore) Get your mate (wife/husband/bf/gf/etc) interested in playing and make in game "date nights"
Mate/child demanding attention and/or don't want to play games? Give it to them then come back an play when they are busy/sleeping ;)
Met my wife online in a MUD in the 90's ;) No issue with wife not wanting to play and our kid is now 18 heheh
