I am confused about the "calling" process, so I am just going to ask the question.

I have the lil can, original can, buck roar, and rattling sticks.

Do you call ONLY if you have seen a deer, or is it OK to use it if you haven't seen anything? Could calling prevent a deer from coming close to your stand? Also, which do you use for does, and which for bucks?

Any input will be so appreciated. Thanks.

Calling to me is always hit or miss especially early on in the season.
When the rut is full swing I use the big bleat can, seems to always bring in a buck or two. Also, when it comes to the grunts and the rattling antlers, I have used them when I haven't seen a deer, and one usually will come in running like bat out of hell, but I've also had them within sight and not move during a sequence... You just gotta give it a try and see, but be sure to give yourself time in between sequences.

Some may disagree but I give it a shot if I get a "gut feeling" it may work.

Rattling was bringing them in this weekend - had 2 different sits where I had bucks come in.

Now is about as good as time to use all of the above, except maybe the buck roar, it would be best during peak rut, but maybe the rut is going full boar in your area? The can, any of them, can be used about any time, except for when the deer is close enough to pin point the source of the sound, in a tree. I often "cold" call with all the calls, but don't over call. Now is a great time to do some rattling mixed with some light grunts. I call about every 20 to 30 minutes, if I'm not seeing any action. If I can see action, but it's obvious that the action isn't going to get close to me, I will call only enough to get thier attention. If a deer looks my way after I call, I don't call again, they often will eventually make thier way to you, and I don't want them to pin point the source of the sound any better than they have when they first hear me calling.
Experiment with calling. I can't think of any time that calling, except rattling, that I've seen deer get spooked away from my location. Don't over call, and don't call when they're looking right at your from a short distance away.

Now is the time. My favorite is rattling. The can is good too along with grunting.