I'll tell you the first week is a challenge, but not impossible by any means!
Backup childcare? Is this because you think you might get too tired? I personally started to gain energy at the end of Day 1, and by the end of the night of Day 3, I was burning up with extra energy. But my nutrition was all over the map with being on Atkins, being off Atkins and eating junk, stalling... I just got fed up and decided I needed to COMMIT to getting the weight off quickly, so I got my butt back in gear this Monday, when I was at 263.8. I have already lost 7.8 pounds in 4 days, woohoo!
You might want to keep the really busy days off for a bit, until you see how it affects you. You also want to be really sure you get in every single MF meal you are due! So 5 plus your Lean & Green, or all 6 if you are doing the Full Fast. Missing a meal will make you faint, weak, and prone to caving into your old food temptations. Ask me how I know
Your first days, I would say it is common to experience a lot of running to the bathroom to pee, heh! Your body quickly dumps all that extra water you are holding as it burns through its glycogen stored in your muscles (and you go into a mild state of ketosis), and any water you might be retaining from old salty meals.
I find that I am very tempted at night to go off plan. But I used to eat take-out at night, and now I have that ingrained habit I am rewiring

If you find this happens to you, or you are just really hungry, it is ok to have an extra MF meal to boost you up and get through this tough time.
I recommend keeping your mind off rich food/drink as much as you can for the first couple weeks. Try not to go out to eat at restaurants, esp. if you are going to watch friends or family dig into some bazillion calorie appetizers or entrees! It's really hard to endure those smells and sights, at least it is for me. Even reading old recipes or watching ads on TV for Chili's is going to make your mouth water, but be strong!
I won't lie, it's kind of like a drug detox. I am definitely jonesing for some pizza, ha! But the weight loss is so fast and I already feel so much better, it is not that hard to say NO to those urges. Eating pizza is just going to keep me stuck in the same very unhealthy place I have been for years. Medifast works, it gives you every vitamin and mineral you could think of past the RDA, it gives you fiber, it gives you water, it keeps you full on a remarkably small amount of calories (imho), and it works FAST.
Come back and tell us how you are doing your first week! I can commiserate with you, but it does get easier, and you will be really amazed at how fast your body changes. I know I am.