Hi Sabrena,
From past gigs attended there I found it quite fast to gain entrance from the gates, there are a lot of Stewarts on. But if you aren't seated and want a good spot standing sometimes its worth going earlier, but I think they are advising no queueing before 4 or 4.30, sounds like they plan to get everyone in quite quickly. If you are not familiar with CP though have a look at which area your seated at as 10 minutes walk can become a lot longer if you have to end to the other end of the Stadium.