I learned little music mixing at my friend studio. You can say a beginner and i am just about to start my own mixing at home. And, thought to make a setup. But bit confuse about speakers. As my friend use studio monitors in his studio. So, i don't have any clue if i can use home theater. I have low budget i don't know what is better for a home setup.
As a beginner, you can use whatever you can lay your hands on.
As you get more competent, you will start to see the failings in your structure & be more interested & knowledgeable in more specific hardware.
The real down-side of mixing on 'non-standard' equipment is you'll have to carry mixes around from system to system - hi-fi, phone, car - anywhere you can listen to it in a different environment - to see if what you mixed is portable, or only sounds good on one system, the one you mixed it on.
Next issue is that, unless you're mixing for movies, 5.1 is no use to you - if anything, it's a distraction.
You only need stereo [& optionally the sub, if your main L/R speakers are not full-range] so to save distraction you may want to completely disconnect the others.
Most audio/Midi DAWs are designed primarily for stereo, though some are 5.1 capable. Most user listening environments are stereo too, so stay away from 5.1.
Apart from that - go for it, knock yourself out.