Recirculation is a wonderful tool for homogenizing your wort. You can either stir the heck out of the mash or you can recirculate the wort. I can assure you that the recirculation is much more capable than stirring.
So you should briefly recirculate your wort at the beginning of the mash, but you'll probably need to limit the flow rate since the permeability of the mash bed is low at the beginning of the mash. I have a manometer plumbed into the bottom of my tun so that I can see how much head drawdown my pump is pulling. Adjusting the flowrate so that the drawdown level at the bottom of the tun is an inch or so above the bottom, has proven to be sufficient for avoiding a stuck mash. You do need to be careful, since a pump can impose a much larger drawdown and that will suck the bed into a impenetrable block.
Since you don't have any heating, it would not be wise to continually recirculate. That would increase the heat loss. I would say that recirculating for maybe 5 minutes would be good enough to homogenize the wort.
Resuming the recirculation at the end of the mash would also be wise at the end of mashing to assure that the wort is nice and clear. I don't think that it would require 15 minutes to achieve a clear wort. I'm betting that just a few minutes are necessary. Having clear tubing somewhere in your pump circuit should enable you to assess clarity.
One caution about stopping a pump during a mash. I've experienced my pump impeller getting stuck on its shaft if the pump is stopped. Now my procedure is to never stop the pump once the circulation has started. I only stop the flow by closing the discharge valve. Needless to say, having a stuck impeller does elicit screaming and cursing, so after a couple of those episodes, I found this solution.
PS: you'll really appreciate having a RIMS tube so that you can maintain temps, do temp steps, and do a mashout step.