This is our first year homeschooling and I was so nervous the first few weeks! We had a similar situation with our school district and had no other option. Now that we're in our second semester it is getting much easier! It you want to use a specific text it's totally okay to start it now, then take your summer break and then finish in the fall of next year. You may find that your kids are moving through a particular text really fast and you'll have to move up to the next level anyway. (we've done both of those now)
