Hi,
I don't believe there is a way to force one feature to finish before another. By design, mojoPortal features do not usually know anything about other features on the page. If you want a particular custom feature to do something after another customer feature loads completely, you might be able to set some sort of variable that the dependent feature can call.
The best method to do this would probably be to build a feature that uses controls/logic from your other features so that you can then enforce any kind of loading pattern that you need.
HTH,
Joe D.