If you're using lash glue for the first time, or if you're trying a new brand, it's always best to do a patch test first. Once you know your skin isn't allergic to the glue, you can go ahead and apply it to your lashes.
Most lash glues come with instructions on how long to wait before applying the lashes. Generally, you should wait 30 seconds to 1 minute after applying the glue to your lash line before attaching the falsies. This gives the glue time to become tacky so that they will adhere better. If you apply the lashes too soon, they may not stick as well and could fall off throughout the day.
Once your falsies are in place, hold them there for a few seconds until the glue sets. Then give them a gentle wiggle to make sure they're secure. You can also apply some pressure by pressing down on them with your fingertips for extra hold. And that's it! You're ready to take on the day with gorgeous, long-lasting lashes!