I work at 4am twice a week. I normally exercise in the morning, but i don’t think that’s possible on those days. Should I do my exercise after work those days or will it screw up the whole routine?

I think you could exercise after work, it doesn’t have to mess up your routine if you make it into its own routine for those days

Exercising before work helps you to be more productive. You can try exercising after work, but if you'll see that it makes everything worse, just go back to your old habit

I also struggled with this, however I realized that the times you workout is arbitrary. As long as you workout and keep your body happy you are already doing a wonderful job! I think it would be best if you completed your workout after work or when you feel your body getting restless. I don’t think if you forget/incomplete/change your workout that you have ruined your schedule. Our days always changing and is different from what we do yesterday. I think you’ll be fine if you move your workout after work.