I don't see anything wrong with dressing them in comfy pants and a shirt at night and for them to wear the same clothes to daycare in the morning. But, you should always change them out of the nightime diaper and, if the clothing is stinky in the morning, you should change that, too. I used to work outside my home when my kids were little. I know any shortcut can mean the difference between running on time or being late every morning. It would also be a good idea to get everything possible ready the night before: breakfast foods as ready as possible, table set, bags packed, etc.
To be honest, there where times back when I did daycare in my home that I showered in the evening, put on my yoga pants and tshirt to sleep in and, if I hit the snooze too many times, I rolled out of bed, put on a bra, brushed my teeth, and answered my door to the first family to arrive. Those kind of clothes look the same if you just put them on or if you sleep in them.
None of my parents even paid attention to what I was wearing. Especially at 6:40 a.m.