It’s highly unlikely that they’ll do any of the SRS before the child is 18. They might start hormones, but in this litigious world medical professionals would be very wary of doing that kind of procedure on someone who cannot give their own informed consent. The sad truth is that the earlier the hormones are taken the better the result would be, but most TG teens have to go through puberty in the wrong body, just to make sure that they know that it IS the wrong body.
IIRC FtM surgery is a different ballgame to MtF, as many FtM would choose only “top” surgery, being unsatisfied with the current “bottom” options.