my bjj club gets shafted on weekdays cause we sublet from an aikido club. as a result they get the normal training times and we get crap. training on weekdays starts at 9pm. i get done near midnight. this is for 3 weekdays. weekends are in the afternoon so it's nice. hopefully we'll be able to get our own club sometime...
IMO don't overthink it. i used to freak out about all this. if you're hungry, eat some food. i sometimes just go straight to bed w/o food, even after hard sessions. your body is not going to fall apart. you'll prob have a big GH release if you don't eat anything anyways. so just eat if you're hungry and sleep if you're tired.
you get better at grappling by learning more anyways. just try to eat well.