I would whip the cream about half way, just as it begins to thicken but before you are at soft peaks, and then add flavorings like schanpps or vanilla.

Get your whipped cream almost done, then add your liquid flavoring. I routinely do this with brandy and Kaluha. The cream should already be fairly thick when you add your liquid.

Mmmmm. . .yum. I add granulated sugar at the beginning to give it a chance to dissolve, then whip it good until it holds a soft shape, and then turn the speed down to medium and add flavoring a teaspoon at a time until I like the taste.