Hi, the answer is no, you have three packs a day, 21 a week and it's all counted out so you could theoretically scoff all 21 in a day so long as you didn't have anything for the rest of the week.
Don't worry how when or where, just have your packs when you're ready to. I often have a breakfast pack about ten after the school run and sorting the baby out then save my other two till about eight at night or even nine when I'm back from the gym, I find I can enjoy them when everyone is asleep.
hope that helps x