Thats just about where I am know, Im still in the determining stages of what services to offer exactly. So far im thinking general cleaning (offices,hair salons etc) Floor strip, wax and maint. and end of lease apartment clean outs.
You are thinking the right way. It's difficult to find enough amount of work providing just floor cleaning services. Try to offer your customers more, like you already mentioned janitorial services. I would suggest also doing carpet cleaning, window cleaning and post construction. It's not that difficult as you think. If you plan to start on your own within 24 month, you can try to work for someone else cleaning carpets, windows and providing regular cleaning services, this way you can get more knowledge in these fields.
If you can offer the customers all these services, you will have more advantage over the competition and you will always get some work, whether it's floor, carpet, post construction, windows or janitorial.
Also think about website, I read somewhere "if you are not online, you don't exist". A lot of people search online these days.
By the way, in what area are you in?