Once the patio is complete, it should not be walked on for at least 24 hours while the mortar sets. If rain or frost is forecast, cover the area with plastic sheeting held down with spare slabs or bricks. Once the base mortar has set, press more mortar into the joints between slabs using a pointing trowel (image 1). Remove excess mortar from the slab surfaces as you progress.
Smooth the mortar along the joints using a brick jointer (image 2) or leave flush according to personal preference. Flush joints will drain better. Clean the pointing mortar with a clean paintbrush (image 3).