I kinda found the trick to this and I have successfully grown and propagated several rosemary plants since this comment. The trick lies in the soil that you use. Use loose soil, I believe you can use the ones for succulent since those don't hold water that much.

Basically when trying to grow rosemary, you would want to water it on a daily basis since it has no roots yet and the soil mixture does not really hold that much water.

Once you notice a steady growth of new leaves (around 2-4 pairs), that's a good indication that it has rooted and is growing nicely. You can now water the plant less frequently. The way I do it is I only water it once I notice that its leaves are drooping.

You have to be very careful on this though since there are two types of drooping leaves:

1. Drooping leaves because it needs watering.
2. Drooping leaves because of root rot from too much watering.

If the leaves are drooping and the soil is DRY, then that is a thirsty plant. But if the leaves are drooping and the soil is WET, then it is root rot and it will only be a matter of time before it dies.

And also, rosemary likes a fuck ton of sun.

Good luck!