FLOWERING 12 hours or less?

hi to all,
i amd getting worried because i need to get my plants to bud before i go away!

they have been growing for about 2-3 weeks and are 1.5ft tall and looking healthy!
they are under 6x25w cfls with a 60w fluro for the lower growth.. i understand this is not ideal for flowering but i am hoping it will do,
they were originally under a skylight in my loft but i moved them because of my worry of when they will flower, i moved them when they were about 1ft tall and seing as i live in UK they have been having about 17-18 hours of light.. (not much direct sun light mind you) i have had them on 12 hours of light for about 5 days now and am desperate for them to bud
1. so they will be finished before i leave
2. because the last time i left flowering this long i ended up with one 9ft beast which diddn't really fit in my loft that well!

is there any way to make them flower sooner?
i am keeping light leekage to a minimum, would a smaller light to dark ratio get them moving or is it just a matter of waiting anf letting nature take its course?

any comments would be appreciated,
thanks:thumbsup: