Oh yes! I know very well that mixture of excitement at being able to do something you love and feeling guilty that you are not spending time with your kids. I started back to work full-time last fall when my oldest started all day PreK, and my youngest went to daycare. My oldest was definitely ready for all day school, there's not doubt about that. The few times he had to miss (fever) he was so mad at me I had to laugh!
My youngest LOVES his daycare. I teach, so I am off for the summer. Today I had the morning with just my youngest (oldest in VBS), and I said, "Do you want to go to the park?" He said no. "Where should we go?" School!!! (That's what we call daycare.)
We don't have as much time together as we used to, but it is more quality time. I'm definitely more relaxed, because I know I'll have my time to focus on my work. I can focus on them more when we're together.