Hi S.!
Hooray for you and all your hard work. Here are some of the things that have worked for me or that I have learned the hard way the past 7 years:
Give yourself time to adjust to a completely different role. For me I was surprised at the conflicting feelings I felt and it took time to sort them all out and adjust to a new life. Even though I always knew I was going to stay home with my kids.
Have a daily/weekly routine with flexibility
Do whatever works best for you and your family and don't compare yourself to anyone else. All families are different and do things in different ways.
Use nap time for YOU.
Simple times together are often the best. Let your kids work alongside you while you do your housework, helping you or playing nearby.
Go for a walk and/or go outside every day if possible.
Rotate your kids toys so they aren't bored and you can bring new things when they tire of them. Have art supplies available.
Find other moms to connect with and help one another with childcare, home projects, etc.
Here's a great book that I like to read from time to time
What's a Smart Woman Like You Doing at Home? (out of print but so encouraging).
Remember to keep the long term perspective in mind when the days are stressful and crazy and exhausting. Many people can do the job you are leaving, but only you can do this one. And the season of little ones at home is short.
Keep a hidden stash of chocolate. :)