Re: Do you mention being a drummer on a day job interview?
It's been a few years since I was on a job interview, but my drumming situation was made known at the time and it was never an issue, and I was able to leave and return several times for tours. A very fortunate situation perhaps, and I had no problem balancing both careers.
But recreational/part-time drumming wouldn't be a problem for an employer as long as you do the job in the prescribed manner and during the prescribed hours. There are undoubtedly hundreds of thousands musicians who have successful day jobs, and also play music during evenings and weekends when many other musicians with regular jobs also happen to be available.
I think an employer might be more concerned about a prospective employee who has no outside hobbies or distractions. Employers like dedication, but they don't always like workaholics who have no life outside the office.