In reply to Queen of the Traverse:
If you mean parking in ogwen, I'd say zero. Usually all the spaces, 'spaces', extremely creative spaces, and even the 'definitely not a space's are gone by 9.30.
Can't speak for the P&R but if you use that check what time the last bus is. Usually, in summer, the answer is far too early. Edit: looks like it's 19:25
Post edited at 13:49