This is how Reader's Workshop is for me, actually this is how my whole day is. I am constantly monitoring many different things at the same time where I may start with a plan but then change suddenly depending on the need of my class. It's not perfect but it works. There may be days when I start spinning a plate and it flops and breaks, but the nice thing is that are a whole stack of plates ready to use. If at first you do not succeed, try try again.
I have found it best to just jump in and try and watch the class begin to take a life of its own. There is beauty during those brief moments when all the plates are spinning perfectly at the same time and you step back for just a moment and breath easy.