how long should I take minocycline for acne?

I've been taking minocycline (50mg 2 times daily) for mild/mildly severe acne for 4 weeks now and have seen great improvement, especially in conjunction with use of an over the counter salycilyc 2% topical medication. I've heard differing estimates on how long it should be taken, everything from 3-6 weeks, 3 months, or 6 months. I've seen a very good result from it: less new breakouts, dramatically less severe breakouts, shorter term breakouts, smaller pimples, more even skin. In conjunction with this I've also done my best to eat regularly, get more sleep, discontinue my habit of smoking, etc. Because I've gotten good results so far, is there a minimum time I should keep taking the drug, eg 2 months? i want to be sensitive to developing antibiotic resistance. thanks much