This is the first time I've had moss so I'm not sure how quick it usually spreads but it has grown quite a bit in the 5 weeks since it arrived. All the plants in my 55g tank are from Aquarium Plants Factory and as you can see, they've all grown SO much since I received them! (For reference, I don't use CO2 and they've still done extremely well!) And maybe I lucked out, but all the plants were/are snail free!
It looked odd at first because of the circular shape of the petri dish but I was able to use some green thread to hold it down to two separate rocks in my tank. The spiky moss has really filled out particularly the one that has more light. It has nice lighter green highlights as it grows. I left the gel on the moss to attach it to the rocks.