There isn't really a better way, because different ways work better or worst, depending on the conditions of the tank.
I have some java moss attach to a rock in the matter of days, i've also tried attaching javamoss to a rock and it ended up taking months. Sometimes it takes weeks. It just depends really, on how fast it grows really, and how you tie it, and how evenly and thickness/thinness wise you put it on the object.
So really, all you can do is like every week, untie your tie, kind of dip it in the water and pull out, and if it falls off, or kind of falls off, ect. Then retie it and let it continue growing. If it stays pretty strongly, then you don't need to tie it.
With javamoss though, if you want a thick dense piece, you'll need to continue to retie it while it grows. I normally just trim mine, because I don't want to mess with retieing. If you retie though, it's worth it. I only retied one of my rocks, and I would deff. suggest it to anyone.
Hope that helps.