Considering the climate changing with the seasons, there will be a certain range of thermal expansion and contraction of ceramic tiles. If the tile joints are too small, it will lead to the adaptability to the environment of ceramic tiles becomes worse, the ceramic tiles will crack once the temperature changes, so we call this joints as retractable joints.
Normal ceramic tiles, the joints should keep around 3-5mm. A special cross locator for this type of tile should be requested from the seller. (Width available for 1mm.2mm.3mm.5mm etc), to ensure that the tile joints are straight and even.
The best time for tile joints filling of ceramic tiles should be 24 hours after the tile paving is completed because the tiles are totally cured then, if earlier, will cause unevenness or looseness of tiles, and pls must clean the tile joints before doing the tile joint filling&sealing.
More techniques about ceramic tile joint filling pls reference to: https://www.ceramictilesealant.com/techniques-support/