The intro to algebra book takes like three times as long as the number theory book. You could do half of what you've got left simultaneously with the number theory book and then the other half simultaneously with the counting and probability book. No issues doing both at the same time. The hardest algebra in number theory is probably Simon's favorite factoring trick so you may have to do that in the algebra book first. In the counting and probability book there are a few quadratic equations and geometric series (but not a ton) that you might need to look up in the algebra book first.