Julie,
I would advise to start with RightStart as your main math program. When switching from one math program to another you are also switching from one philosophy to another. I advise starting with the program you plan on using.

By the sounds of it with your child, you could begin RightStart now and then continue on through the program. With level A, there are many activities and things to do that you can stretch it out as long as you need to, anywhere from 2-5 days!

Also start playing the math games as soon as possible, this will reinforce the concepts taught throughout our lessons!

Thank you for giving your child a RightStart in mathematics! Let us know if we can be of any assistance!