For the OP. I used to run a perpetual room when I grew. Like others have stated it's best to maintain mother plants. Every 6 months or so is when I would replace the mom with some cuttings. It is best to cut from the top of the plants. I noticed that when I took cuttings from the lower 3rd of the moms, the subsiquent clones tended to be not as vigorous as one taken from the top third. As far as the schedule goes, if you clone every 2 weeks, then you will harvest every 2 weeks, If you clone every week then you will harvest every week. The main factor is how often you can take cuttings. You want the moms to be healthy and vigorous when you cut them, that leads to healthy vigorous clones. With the limited space you have to work with, 1 mom should be sufficient, after 3-4 rounds it should be bushy enough to allow you to take all the clones you need. I would suggest taking twice as many as your target and keep the strongest ones. think of your perpetual grow as a pipeline, you clone, you veg, you flower. It will be batches that get transitioned to the next stage of development.
As some have said you can take clones of clones of clones, but at some point the genetics COULD have some mutations or abnormalities. It usually takes 2 weeks for roots to pop, and then at least 2 weeks of veg before flowering, unless you wanted REALLY small plants in your SOG. But once you have your pipeline established and are cloning on a schedule (I'd recommend every 2 weeks) you just follow the routine and keep your pipeline full. Your veg and flower room will have plants at various stages of development.