I think that is a good approach. Not so long ago you were not allowed to write anything on your answer book for the first 15 minutes and I think that was a great way to enforce reading and planning time. I’m sure that rule was abandoned because in a large exam room it was impossible for invigilators to easily tell whether candidates were writing on answer books or making notes in question papers.
Remember the 5 Ps: poor planning produces poor performamce.