When should I start preparing?

My parents are getting on my case about starting to study for the ACT, and I was wondering when is the best time to start studying? Also, I am weaker in math and science will a tutor help? Finally, is there an online program or test prep site that is the best for studying? Thanks!

What grade are you in?

I’m currently a junior.

Shoot for the April and/or June test dates. Begin prep in January.