unpredictable job schedule

Something I need to do that would help me in a certain category, but the problem is, I'm looking for an "ideal" time,because if it involves the person calling me back, and I'm driving...but with my unpredictable job schedule{and not knowing when they'd call} wrangling with the timing is the...

There are several things I need to do and take care of upon me, all kind of "deadline" things, but because it's a "narrow tightwire",where because there's several of them, and an unpredictable job schedule where I could run late with something and not have enough time in between the next...