Lots of different ways to handle it, but one night a week to start seems reasonable to me, maaaaybe two. Three is almost half the week, that seems like a lot when he has not only you, but also housework, time to himself, and the rest of his life to think about.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.