Snails, like frogs, will show up on there own. Don't worry about stocking them. The little harmless parasites (yellow or black grubs) that you commonly see in the flesh or on the scales of freshwater fish use snails as part of their life cycle...

Grub on fish...bird eats fish, bird poops in pond, grub babies get back into the water and find a snail to live on/in, grub matures and transfers to fish...repeat!

Your plan is pretty solid.

You could add your forage fish when the pond is half full or so. This might gain you some forage reproduction depending on how fasts it fills.

Adding fertilizer may not be necessary. I never have, but it depends on your water and goals.

Adding crawdads can be a good adventure...I'm on the fence about mine, but still liking that I have them. I would advise stocking them at the same time as the big boy fish depending...meaning...stock crawdads that will be too big for the game fish to eat their first year in the pond. Crawdads, around here, only reproduce once a year in the spring. So, if you stock crawdads (even at a rate of 25/acre) a year before you stock fish and if they reproduce well...the new big boy fish (assuming that they are fingerlings) may not get big enough to control the craw recruits and you'll end up with a lot of craws that get out ahead of the stocked gamefish. This could result in too many craws. One crawdad turns into 500 without predation. Don't ask me how I learned this lesson. If you do decide to try craws...put plenty of rip-rap rock along some of the bank from the dry ground down to at least a foot of water. I would say 10 to 25% of the shoreline. To many craws will likely eat any veggies that try to start growing. They really like the submerged plant varieties at my place. The emergents do much better, but both are good for a pond. I cannot get any type of the submerged varieties growing in my pond as the craws devour them and they keep the water pretty muddy so the bottom of the pond does not get any sun. Here's the catch, craws have very good benefits (they like to eat FA and they provide good food for the fish), but they also have negatives (they also like to eat your desired plants and can muddy the water in high numbers)...finding that balance may be more up to mother nature than you. Enough on crawdads...for now!

Fish on!,
Noel