Locking: The time it will take for your dreads to lock will depend on your hair type, how tight they are from the start, how often you wash them, and how much you work on them with the crochet hook. If you’re diligent, probably 2-4 months. If you’re lazy, probably 4-8 months. The more you go through the cycle of washing them which makes them frizzy, then re-tightening with the crochet hook, and locking it in with palm-rolling, the faster they will lock. Everyone’s hair is different. Even once they “lock” dreadlocks are still ever-changing, they are never just "done."
Root Tightening: If your dreads are done properly, they should dread for the most part on their own as your hair grows out. It depends on your hair type. Sometimes they won’t, and there are little things you can do to help them along. First of all, separate your dreads. My theory is that when you rip them apart, some hair around the outsides of your dread will break and this is actually a good thing, because then they can tangle back into the dread. Next, if a dread grows out an inch and a half or more without dreading, I find “looping them through” helps. Take the end tip of your dread in one hand. With the other hand, poke your finger through the middle of the root area. Take the end of your dread and stick it through the hole and pull it all the way through. This kind of twists the hair in tighter. For a really loose roots, do this a few times, but make sure not to go through the same hole more than once. Pull it through a new hole going in a different direction each time. I know that is confusing to read, ask me to show you. After your dreads are separated and looped through as needed, you can use the crochet hook to tangle in any loose hair at the roots, which will help them stay dreaded at the roots as well.