I am an Executive Platinum member. I have flights from DFW to LHR, FCO, OGG & HNL. I am trying to figure out the timing of how long to wait for the Upsell price to go down for an upgrade to Business class. Once I put an upgrade request with SWU, Business Extra Upgrade or Miles & Money the upsell offers stop. How far out before my flight should I wait before requesting the upgrade?