Based on PANS-OPS, what is the earliest turning point that can be used in a missed approach?
I can not figure out the earliest point where turning is allowed to be initiated, during a missed approach.

It is up to the designer. Nothing in PANS-OPS prohibits turns before MAPt but in that case an additional area extending from the earliest FAF needs to be protected as shown in figure I-4-6-14 PANS-OPS Vol. II.
Because early turns are not always feasible, advisable or convenient, we often disallow turns before MAPt, in which case a note to the effect will be added on the profile view of the approach chart. Any turns &gt;15° will then be executed in the final missed approach area (Vol. II I-4-6-10 6.4.6.3.1).