" Choke " is really a misnomer on Dellorto carbs. The system is actually a fuel enrichner.
Pulling the plunger(s) levers adds fuel for a very rich mixture, which helps the cold start. Guzzi motors cool down very fast due to the extensive cylinder fins, and, unless you live in a very warm place, the "choke" is usually needed after 1/2 hours from killing the engine. However, depending on the set up of your PHF accelerator pumps, you may be able to achieve a similar effect by twisting the throttle fully a couple of times before hitting the start button.