Well , excuse me because neither of those questions has a clear and absolute answer.

I want to know how much I need to practice to animate to become and pro (or amateur lol).
Like , I'm practicing 1.5 hours a day min.

I also want to know how good I can get using only my mouse.
I can't get a drawing pad so will I have too much trouble without one?

Just practice as much as you need to, man.
You don't need to limit yourself everday.

From what I observed, it takes more than a year of practicing 2D stickfigure movements to make watchable animation. I don't know about this recent influx of animators who use "angles", but it seems like animating in "angles" takes a shorter time to master ("angles" don't look that impressive tho tbh). A few months to more than a year for decent effects. Making backgrounds really depends on whether or not someone has been drawing a lot before animating. If you're talented, then things come more naturally, but if you're not as gifted then I think my assessment is fair. There has been some people who can animate well with mouse, but generally, mouse animators don't bode well. It takes way more effort to make consistent lines. terkoiz used to animate with mouse, and iirc he made shock 1 and 2 with mouse. Maybe even 3, idk, someone correct me if I'm wrong.

That's me answering your questions. This is me telling you that if you only animate to become a "pro", then I think you're going the wrong direction bud. The animators who you see can make great animations are the ones who actually enjoy animating. They didn't worry about how much time they need to practice everyday. They didn't worry about not improving as fast as the next guy. They really just made a lot of animations that they thought were fun to make or were cool until they got the hang of it. People who animate to become the next terkoiz or something usually leave after a while because they realize that animating is hard. Where you stand depends on your attitude towards animating, and 8 times out of 10, people who ask how long it takes before they can become pro will quit and leave. The remaining 2 out of 10 are people who quit animating but stays on stickpage and tells beginners that they suck and that they'll probably quit sooner or later.

Honestly, pretty much the only differences between a mouse and a tablet is the difficulty, and pen pressure. I made it all the way to high beginner with just a mouse. But once i got a tablet, animating felt like the easiest thing in the world. So i highly recommend you start up a paypal, start finding ways to get some money online (got mine through an SP competition here) and buy a tablet on amazon or something. I've found one for only $45 on amazon and it's pretty nice quality. I can link it if you like. But it's not entirely impossible with only a mouse. You just probably can't make it to pro without a tablet. And as for how much you need to practice, a lot. If you're completely new to animating, i warn you that it's much more difficult and time consuming than you think it'd be. I've gone through 2 years of vigorous training, and I've just gotten to intermediate level. Of course I'm not planning to stop there. But many of the pros you see here already have as many as 10 years of experience under their belts. Again not saying it's impossible, but it'll be pretty difficult. And more often than not, it's worth it. Hope this helped.

I was thinking about getting a tablet sooner or later , just asked if I need one now or if I can also get it later.
I'm not animating to be a pro. I enjoy it , I spend at least 1 hour on my pc everyday so I thought why shouldn't I do something I enjoy.
And I'm not worrying about time , that stuff I have enough. I'm 13 and , maybe it's too soon to talk , but I want this to be a lifelong hobby.

If you're going to get a tablet to animate stickfigures and stay with that, then buy a really cheap one or better, don't buy one at all.

It's a waste of investment to use it for stickfigures(Which personally is sad) and for nothing else. You can, however, get one if you feel the need to. Also, animate with a goal in mind rather than the time. There will be times in which you have to fix a scene or redo it all over and that takes a lot of time. Instead of measuring by time, measure by the goals you want to achieve(Such as "Finish this scene in a span of 2 days").

Oh and you can go pretty far with mouse if you'll animate stickfigures. It just requires more effort.

I think I'll get a cheap tablet. I've seen ones in amazon that cost only 30$ and have really good customer reviews.