Well that would depend on if there even mature enough to be flowered,check your plant for alternating nodes,that is the sign for maturity...if not then you could be waiting awhile and wasting time when you could switch back to 24/7 veg until mature or losing precious yield by force flowering,NOT to mention stressing your plants which could also cause a potential hermie....Also if its sativa dominant and mature give it some time,sometimes they take awhile depending on there geographical origin...if not mature..YOU COULD BE WAITING AWHILE...cheers bud...