Yes, they can be used as an effecient tool in gaining muscle.
Optimum time to ingest one would be 20ish minutes post work out.
You can also opt to ingest some prior to going to bed (if its a low fat, high grade protein ... not a WEIGHT gain protien ... big difference).
Ensure you that you drink plenty of water while taking protein supplements, as this will help relieve the stress to your kidneys from processing the increase in protein.
Hope that helps. If you have any other questions, feel free to ask via PM.