Trying to figure out if it’s worth it

Just had a consultation where I was given a treatment plan of 4-6 months, and the price was affordable for me. At the current moment my teeth aren’t too bad and my smile doesn’t really bother me, but my fear is that they will get worse over time if I don’t get this treatment and eventually I will actually really need it. I’m sure it depends on the person/other factors but do slightly misaligned teeth typically get worse with age? I’m 26 right now. I have a habit of mouth breathing too so that probably doesn’t help. Just trying to decide if I should start now (it would be inconvenient) or wait until I clearly notice my teeth getting worse.