How long does it take for change of status to H4 with I-765?

Hello, I am currently on OPT and planning to apply for COS to H4 with I-765. My question is does anyone know how long does it take to get approval? I know we can track processing time at Processing Times but they are not accurate, so if anyone have real experience that would be great to know.
Thanks for your time to review my question, I appreciate it!