I recommend somewhere along the water on the Canada/UK side, with no trees in front of you. The launch will appear on the opposite side, above China/Norway/Mexico, usually just north of true east. Having the water between you and any trees/buildings on the horizon will make it easier to see and maximize the time it is visible. It does take a few seconds to appear above the horizon, so be patient. I do recommend that you have live launch coverage on your phone as sometimes they get scrubbed with seconds to spare, and it will save you waiting around for nothing.