each day varies quite a bit.
Some days (usually mondays and fridays) I just feed them in the morning, then check on them before I go out in the evening. So probably 10-20 minutes?
Other days I spend the majority of the day and evening in the garden with them.
What I like about rabbits is that they're happy enough whatever you want to do. They don't crave attention so wouldn't care if you barely saw them for days on end, but are still interested in you when you want to go out and spend time with them.