I am in Kathmandu now and plan to do a short trek in Helambu. I assume I will need a Tims, and want to get it tomorrow, Friday.
But I can't remember where it is you get it, nor what will be required in the form of photographs and money.
I checked the FAQ, but the info I found there is rather dated. The links I checked all lead to posts from 2007, wherein for instance one prominent member of this board tells us that Tims can be had from an office behind Fire & Ice. That was certainly quite long since.
No, I do not avail myself of either trekking agents nor a guide.