The first thing depends on the type of patent you apply for.
1. Invention patent: long cycle, about 2 years. Because it is difficult, acceptance does not mean authorization.
2. Patent for utility model and appearance: short cycle, about 6-8 months. Because there is only a formal review, it will generally be authorized after acceptance.
I don't know whether you mean the third applicant or the third inventor by the third author. If the third applicant can apply for a copy of the patent certificate (in the case of multiple applicants, only the first applicant can get the original patent certificate); If it is the third inventor, there is no certificate to take.