Is there a similar way to find out for developing time as well?
You can measure that out with a reference Grey card and a densitometer which is a calibrated instrument to measure density. But that is an expensive instrument.

Good starting times you can find here:
http://www.digitaltruth.com/devchart.php

The stop bath is only meant to get an exact developing time interval and to prolong the life time of your fixer. 30s-60s is enough for this step.