Best 2 Weeks to Cut?

Hi everyone - I’m in week 12 of Higdon’s intermediate 1 plan based on doing Philly on 11/24. Just learned of a conflict that will prevent me from doing the race that day. Incredibly frustrating as it’s my first marathon and I did the Philly Distance Run a few weeks ago.

If I cut 2 weeks from the plan in order to do another nearby marathon on 11/10, is there a strategy for which weeks to cut? Plan looks like a 3 week taper. Is 2 weeks enough? Maybe cut a taper week and a week before the first 20 miler?

Appreciate any feedback! My goal is 3:30. Time in Philly half marathon was 1:38.