Before you do OSCP, you will never know, whether you are ready for it. Once you are in the labs, you will realize, that 70 machines on vulnhub is absolutely enough.
The labs are kind of different than HTB and vulnhub, but you should already have a solid baseline, so I don’t think, that you will struggle.
Before I did OSCP, I had about 40 machines on HTB and about 20 on vulnhub. In the end, I was overprepared for it, so just start today 