Short answer is yes, run the letro all the way till you start the PCT. You will likely get an estrogen rebound once you stop taking the Letro. So be prepared and have nolva and the rest of your pct set to go the next day after your last dose of Letro. Not sure that you need aromasin for pct with the nolva and clomid combo.
Honestly unless you have already statred I'd get a less harsh AI than Letro, like Adex would work better imo. Folks are probably going to tell you that your pretty light in weight but I'll leave that one alone.