Would they not do the usual thing. If they have 33,000 tickets then they look at 32,000 (or 28k or 30k) people and the first tier is for them, e.g. STH and bronze members with xx loyalty points?
No 3pm Saturday is the default for both semi-final matches on a lot of websites. It actually can't be that and be shown on TV because of the 3pm Saturday TV embargo. It will be 5:15 Saturday probably.