Make sure s/he's on-board with the objectives, make him/her part of the estimation process, agree targets (features, fixes, etc) with timescales, point him/her

Make sure s/he's on-board with the objectives, make him/her part of the estimation process, agree targets (features, fixes, etc) with timescales, point him/her in the right direction and let go. Hand over the responsibility. Occasionally when passing ask how it's going, whether it's ahead or behind. Check roughly every day or so, asking if there's anything needed to unblock progress, or if it's going well. As you work on the agreed timescales/workload, hours will settle out naturally. Let them work whenever they like to achieve the goals, but make sure they're in fairly frequently so you have the communication. All this can be mutated, but that's what works for me.