Use a shaving mug, coffee cup, lathering bowl or even your sink. Only use warm water not hot! Try not to soak the brush past the bristles or hairs. Time can be anywhere from 2-3 minutes or however long it takes you to shower.
Take your soap in one hand and your brush in another. Swirl the tips of the brush on the soap in a circular motion. Do not use much if any pressure. Just enough for the bristles to splay slightly. Load in this manner for about 30-60 seconds. Check your brush and you should see the tips are fully coated with soap. Don’t be afraid to go back to the soap and load a little longer if you don’t have a nice coating. One tip I’d like to mention and this works extremely for our shaving soaps. Swirl with a dryish brush for about 15 seconds, add a few drops of water to the soap, swirl for another 15 seconds, add more water and repeat for close to a minute. This will help you to build a beautiful photo-lather that is shiny, properly hydrated and has the consistency of a very thick cream.