It can be a bit difficult to tell when a pavlova is done (for beginner pavlova bakers). For one, you don't want to keep opening the oven to check as this will cause cracking and fallen pavlovas. It's better to overbake a pavlova in my opinion and have it crisper than too chewy. Two, you want to bake a pavlova at a low temperature of 235˚F and if possible on a convection setting.  This is to slowly dry out the meringue at a low consistent temperature. Your pavlova will be done when the outside is completely crisp to the touch and can easily be peeled/lifted off the parchment paper/baking tray. Baking time will vary depending on the size and thickness of the pavlova.  For this reason, add extra time for thicker pavlovas. You can be looking at anywhere between 1-3 hours of baking time. Use your recipe as a guideline as no two pavlovas are the same size.