What is actually required is 70 hours P.1 in total before a MEP class rating can be applied for. The test can be taken before that.
There is however nothing in the rules to stop a suitably qualified instructor to authorise a solo flight in a MEP aircraft. In theory you can still do your PPL on a twin, do your first solo on a twin, and get a PPL issued without ever flying a single. Problem would be that you need to do 70 hours P.1 in the twin, authorised by an instructor. It's clear that this is not the intention of those who wrote the rules (they want people to work their way up the SE ladder), but it is possible.
Regards
Gerard