Reading some of the replies on here, oh dear

It is not unheard of for an absess to burst inwardly, so pressing/squeezing the pus filled area is not something I would advocate, unless the VET had seen the wound and given that specific advice.

Someone I know had a very similar situation to you, and the advice they got from the vet was completely different to yours. I'd be concerned if I had to wait 3 days for an appointment with my vet.