The amount of time to spend with a child is a personal decision. The more time you can spend with your child the more you influence their development. I am also a working parent and struggle with this myself. Child time in our house is a balance. We plan our schedules to the best of our ability to include as much "quality time" The thing is this is our plan. Our plan may not work for you as I am sure our schedules are different. What you need to do is find what works for you. If you enjoy your evening workouts then try to see if the child's father can be there to have time with them. I also suggest you try different arrangements. Maybe one week you try to work out before work and another week you try during you lunch hour. I have also found fun ways to include my children in my work out time. We run in the park, we do dance in the home, we lift weights and she is my cheerleader. By including the children you are teaching them how to live a healthy lifestyle as well as getting your exercise in.
I hope this answer has been helpful and you "accept" it. If there is anything else I can do to be of help please let me know.