Am bottles?

This is a bottle feeding question (still breastmilk).. so I’m going back to work soon and some days my husband will be home with our son. Do you wake up baby before you leave to feed? He sleeps really well in long stretches, and right now he wakes about 8-9Am. If I leave him asleep and go on to work, how much do I feed him from a bottle? Usually he sleeps 8-12 hours so that seems excessive for a bottle. He usually does 4.5oz every 3 hours if taking bottles.

I’m probably not going to do it often, but if I’m late or something, I’d like to know what to do.