My vallis i've had for about a month
I bought 8 plants that were 20-30cm high
I know have 6 new sprouts growing between 1 and 10 cm high
The elodea I've had for 1 week now but they haven't really grown yet.
I'll finish off with some anubias nana in the following weeks, when my elodea have established their roots firmly so they won't go floating when I move the gravel around
As for the snails, I got them too, maybe 10 or so I've found so far. I put a betta in my tank for one day and he got rid of most of them to my surprise. Some people also dip their plants in a 5% bleach solution but I wouldn't try that...
One thing you can also do is squash the snails and your fish will usually eat them.
You could also put a small piece of lettuce in your tank with some gravel over it to sink it. In the morning, just lift the piece of lettuce and throw it away and repeat until you have no more snails!