Ladies I need advice

My son is 16months old. He has 8 teeth and another little one starting to come out. My question is: do you brush a 16months old teeth before breakfast? Why I’m asking is because, my child wakes up crying to have breakfast. ( he sometimes wakes up at 5:30 or 6 in the morning) so when he’s crying all he wants is food. So I give him food and brush his teeth later. Is that normal? Give me your advices