What should a beginner's daily prayer rule look like?

This really needs to be talked about with your priest, but a general guideline is somewhere in the neighborhood of 10 to 25 minutes in the morning and the same in the evening. That will vary with your way of life. A stay-at-home mom with three little kids may find it quite difficult to say that many prayers in the morning because she's been nursing a baby all night.

So talk with your priest. But normatively speaking, you can't really spend too much time with God. It is not a race to the bottom. Keeping the morning and evening prayers as they're written in the Jordanville Prayer Book is one of the best guided ways to learn how to pray, to stay structured, and to bookend your day with the remembrance of God morning and evening.