It will most likely take quite a while for you to notice any green algae. Snails will in fact help the diatoms, or they would if they were to survive in your tank, but they probably won't because of your trigger.
But now to the more important issue--you did add too many fish--too fast--before you even cycled. These fish don't have great odds of surviving, although it's possible. Here's a few tips in case you aren't able to return any of them.
Monitor your levels daily!!especially that ammonia.
Keep some kent ammo detox on hand, odds are you're gonna need it.
while normally you would not do water changes during a cycle--you're going to have to, to preserve your livestock. When your levels become unsafe, change it, even if they are larger amounts like up to 50% if needed (which normally is inadvisable as well)
plan on getting a bunch more live rock if you can
but NOT immediately because in the very beginning that too will add to your load, as opposed to later when it will become a very valuable filtering tool, and the magnum might not cut it.
While there are varying opinions on this stuff, I would add a bio-booster like cycle (or something) because you need all the help you can get.
Last but not least I would cross my fingers.
If you have any questions about my or the others responses, please just ask. Sometimes you get more than what you bargained for around here.
FYI-your pretty new white cc bed will never be like it is now, but when you vacuum it, it cleans up pretty good.
Good Luck to you (and your fish!)