Can I start my dreads with dread wax and then stop using it early? - Dreadlocks FAQ's
Normally Dread Wax is used until the dreads reach the level of tightness you're looking for. This usually falls between 1 and 3 months depending on factors like maintenance, hair type, section size etc. If you stop waxing them before they are as tight as you like then you've stopped waxing "early".
Will your dreads fall out? No....Well, I won't say there's no chance of them falling out since I have no idea what the backcombing was like or what size dreads you're making. Dreads that aren't properly backcombed can't be saved by Dread Wax. Good knots are required for the wax to do it's job (which is to help those knots compress and tighten as you palm roll and not loose their progress when you're not palm rolling).
Assuming they were backcombed well, and on their way to locking up, not adding further wax should just extend the time they take to lock up. You'll probably have more loops and zig-zags form in them and you'll likely have more loose hair to pull in, but eventually they will get to a very similar place, it's just a matter of time and effort.
Even when the waxing is stopped right after the initial waxing the dreads still benefit a great deal. If you look at the amount of wax that is added after the initial serving you'll see it's quite small. This is because very little wax is needed to help the knots keep their progress. When the tightness of a waxed dread and an unwaxed dread is looked at over time you can see that while the wax benefits the locking until the dreads are tight, the fastest and most dramatic change in the compression of the dread is seen in the initial palm rolling after your first waxing. That's when the core of the dread is formed and the hair begins finding it's place around it. So after the initial waxing and palm rolling you could hold off on further waxing and your dreads would likely succeed, they'd just get where they going a bit slower and you'd have some extra work and loops along the way.
Because hair type, section size and other factors change things so much it's impossible to guarantee the results with the Dread Kit unless the Dread Wax is used until the dreads reach the desired level of tightness.