Herbilady,
I wouldn't worry about feedng anything special before bedtime. If you've got a good quality chick starter, it will have all the protein they need in it. When we were brooding chicks last spring, we got into a little routine. While I was cleaning the brooder, my daughter would play with the chicks on a towel spread out over our coffee table. She'd weigh them and record their weights. Regular weigh ins are something we do with our indoor birds, and it's a great way to chart growth as well as spot any problems that might be developing early on. Weight loss in a chick would be something to pay particular attention to, of course. It helped me relax, a bit, because I could see those gram numbers going up nearly every day, usually by leaps.
Thinking back, I remember we spotted the big crop on our first chick quite suddenly, so they don't have it everyday. It's something we didn't have to feel for, it was obvious visually. They looked like Dolly Parton, but only on the right side (if you know what I mean). It wasn't every night, so I wouldn't worry if you don't see it, as long as your chicks seem to be eating and behaving normally, not acting sick or lethargic. It also may be that yours are too young yet for this stage.
The other thing people often worry about is when they see their chicks stretching their necks and yawning. Newbies often think this is a sign of gapeworm or something else awful, but it's most likely the chick just rearranging food in its crop.
I used to worry about everything last spring, but my five chicks all survived and grew into healthy adults. This year, I'm much more relaxed, but I have mother hens to do all the mothering instead of me, this time. I guess that makes me a chicken grandmother!