I didn't get in on Saturday as there was a huge queue and 250 people were already in there, even though I was there at 1pm. However, I asked the steward on the door and he said kids are allowed in.
The huge queue moved really quickly. I only waited for 5-10 minutes at the most around 1:30. Giving it some thought though, last week might have been the exception rather than the rule: with all the opening game pre-match activities, a lot of folk might have been moving into the ground around 1:30. On a normal league game the move from Dick's -> ground might not really happen in any volume until 2:30ish.