One thing I would encourage as you begin is to be flexible. It takes some time to try different things- like schedules- and find out what works for your family. One of my favorite things about homeschooling is the ability to adapt to the individual needs and preferences of each child. That means you may use pieces of many different scheduling suggestions, and adapt as you go until you find something that works. Don't expect it to be perfect the first time!
My oldest nephew (11) is very self motivated and likes to work independently. My niece (9) needs a lot more guidance and enjoys being creative and artistic. he starts school on his own at 6:30 and is usually done by 12 or 1, while she gets started around 8:30 or 9 and finishes sometime in the afternoon, depending on how motivated and cooperative she is

Another note specific to ECC: the first two weeks can feel a little overwhelming as you learn what book is used when, how to use the teachers manual, etc. The third week starts a routine that continues the rest of the year spas you visit different countries. Give yourself Grace those first two weeks! Expect things to take a little longer than you plan. Expect to keep kids waiting while you remember what comes next!
My final suggestion is to stagger start times. Starting all of first and ECC with all kids could be overwhelming. You could stagger starts many ways, but it may look something like this: start math and language arts with older students week 1. Start first grade and 2nd grader math and LA week 2. Start ECC week 3 (meaning week 1 in TM), perhaps skipping a few days of math/LA. Everything up and running week 4. I'm sure this wouldn't be everyone's preference, but I think it's a nice way to ease into the school year, especially your first year homeschooling!
Hope to hear how things end up going for you!