Happens lots at my unit. Ten minute call is an AIP recommendation and definitely good airmanship.
We can (and do) use 5 minutes from the holding area as a procedural separation but if you are given a level by the Approach unit, you should climb/descend to that level straight away unless told otherwise. We occasionally use the phraseology "arrange your flight to be level by time xx" or "when ready, climb/descend"
Good luck on the test!