Is it possible?

would it be a good idea to put a plant into the flowering stage when it is a bout 1 ft. tall to determine sex the clone and make it a mother plant?

That depends on what your trying to accomplish. There are two ways to do this. The 'proper' way is to take clones from the plant, root the clones and then put them in flowering light to determine the sex of the original plants. In the meantime cut the growing tips of your potential mother plant, this will force branching, so by the time you know its sex, it will be ready to produce many babys.
The other way would be to take clones from the plant, root the clones and send the originals into flowering light to determine sex, cull all of the males, choose mother plants from the known female clones you have.
I just posted a picture of the resulting clones from both methods and I'll repeat it here. The advantage of the proper method is that you will have mother plants that are producing large numbers of clones faster. The advantage of the second method is you will have some bud to smoke about 4 weeks sooner, probably not enough to get you to the next harvest but some.
Both methods work and I use the second one for the strains I experiment with. The reason I do that is more for room than efficiency, my mother table is already full.
The ones on the left were taken from fully developed mothers on 11/30. The ones on the right were taken from plants just as they went into flowering on 11/8. The ones on the left went into flowering on 12/14. The ones on the right will go into flowering in a couple of weeks. Get the picture? VV

i wouldnt cuz u get less yeild for sure mate let it grow take clones then make the clones ur mother and flower the other plant from the start....

alright thnx for the input