Have you already made a first confession when you were a child? If so, you could return to confession anytime. If you have not made a confession yet, you would need some instruction in the sacrament first. You could ask your pastor for information on how to prepare for a first confession and then confess when he believes you are ready. Although RCIA classes can be helpful for returning Catholics to re-acquaint them with their faith, it is primarily intended for the catechesis of unbaptized non-Christians. Non-Catholic Christians and returning Catholics should not be delayed from receiving the sacraments solely to accommodate the RCIA schedule.