As for the original question... I usually masturbate whenever the urge strikes me, which is usually at night when Amelia's at work. If I do, I'll usually do it twice a night... but I can go a couple of days without it.
As to where... it's either in the bedroom lying on the bed (with a nearby towel for handy cleanup) or in the bathroom before I take a shower. (I usually don't masturbate IN the shower... it's been a while since I have).
As for Amelia... I don't really know. She doesn't provide me with a schedule.