With a well-paying job you don't really need a bank roll for micro stakes, just refill when you bust. But if you are serious about having a separate bank roll for poker, that is not supposed to go to zero, you'll need to start lower than NL25. 12 buy ins is not enough. Alternatively, if you think you're at least a break even player at NL25, add another $300. That should be enough, but be ready to move down to NL10 in case of a downswing.
Also, there is a better forum for these kind of threads:
https://forumserver.twoplustwo.com/1...r-blogs-goals/
Finally, good luck and all the best for you!