How long until Flex Glue is waterproof?

Excuse me, I'm curious about the waterproofing capabilities of Flex Glue. Could you please clarify how long it takes for Flex Glue to become fully waterproof after application? I'm interested in using it for a project that requires a high level of water resistance, and I want to ensure that it meets my requirements. Additionally, is there any specific preparation or post-application steps that I should follow to ensure optimal waterproofing? Thank you for your time and assistance.