Hi Marcel,
First of all, a warm welcome to CodeRanch!
I definitely agree with Jeanne. Just go for the OCJAP7 exam.
No need to wait for weeks or even months if you want to take the OCPJP as well. Currently there aren't even exam objectives defined for the OCPJP8 exam. So that will probably take months until the beta version of this exam is released. And then you have to wait +-11 weeks until you know you passed the beta or not. And because the exam objectives are unknown, there is also no study guides. So the Java 7 exams are both already available, study guides and online resources are available. No need to wait at all!
So the Java 7 path is definitely the best choice at this moment. And once the OCPJP8 is available you can take the upgrade exam, to become OCPJP8 certified (if you want to, of course

)
Hope it helps!
Kind regards,
Roel