Certified GKH Gardening Expert
It's best not to prune pin oaks during the spring, except to remove dead branches. It sounds like your trees' branches are most likely alive, and they will probably produce leaves later on, so the best thing to do is wait and see. They might be late in getting started this spring since they were recently planted.
If you do suspect that a particular branch is dead, you can use this test to see:
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-scratch-test.htm
http://web.extension.illinois.edu/askextension/thisQuestion.cfm?ThreadID=12020