Teeth Braces (Damon Braces). How long do I need to wear them? (Photo)

My 1st Teeth Braces (Traditional) ard 6 yrs ago. Wore it for 1 1/2 years and wore a retainer for 2 yrs, and lost a retainer for 1 yr. I just had my Braces (Damon Q) yestday. My lower teeth not so bad but my dentist insist puting a damon braces next month. And he also said my upper and lower bite not so align. My quest is,looking at my photos, can you please tell me roughly how long do i have to wear it? This time, after tooking my braces off, im going to have 2 retainer just in case i lost it.