I am fascinated with this idea so summer 2015, I will do it. If you would like to be involved, sign up. It will be a fun experience.
Entrance fee: experience models ($75), aspiring models ($150)
There is a standard definition and there is a standard definition modified for each professional.
Basically, in TF shoots both the photographer and the model are working for free, to benefit both of their portfolios. Neither is paying the other. Both are contributing their time for images. TF stands for "time for..." this term describes a common arrangement between photographers and models.
The model and photographer share rights to the photos depending on agreement. Both can freely use the images for self-promotion, in their books or online portfolios but neither may sell them unless both parties come to a separate agreement for that. So, no posting them to members-only areas of paid websites, etc.
If there are additional fees like studio rental or having a hair/makeup artist (who isn't also working on a TF basis) then the model & photographer split those costs depending on agreement. Majority of the time, the model would be prior hair and makeup ready. Outfit ready depends on project/shoot.
In TFP, the photographer provides a previously agreed-upon number of finished 8x10 or 9x11 (etc) prints from the shoot - usually whichever shots were the best.
In TFCD, the model receives a CD of images from the shoot, usually all images taken, unedited. This is normally provided at the conclusion of the shoot or within a day - however long it takes for the photographer to upload the shots to his computer and burn a CD.
In TFDC, the model receives an email or virtual download link of the images from the shoot, usually all images taken, unedited or whatever agreed to in writing. This is normally provided at the conclusion of the shoot or within a day - however long it takes for the photographer to upload the shots to his computer and upload.
Since retouching/photoshop work is time-consuming, if the model prefers a smaller number of edited images instead of all the unedited ones, a reasonable amount of time is allowed for the photographer to send that - usually a week or so. But I advise against it - many photographers are quite busy and TFP/TFCD/TFDC shoots take a back seat to any paid gigs (or their 7-4, 8-4, 9-5, 10-6, 11-7 or so jobs) so it might be a few weeks before they realistically have time to sit down, sift through 50+ images from your shoot and do editing for a gig that's not helping them pay bills. Others are just flakes or rip-off artists who don't hold up their end of the bargain.
The world is full of prospective models still waiting for prints a month after their TF shoots. So I recommend getting your images asap, and deal with retouching later if that is in the agreement.
At the end of the day, the model can not be upset if they apply for a TF project and not chosen. Photographers, depending on the model, she can cancel for a paying gig depending on written agreement. Models, if you already have a written agreement, you can not cancel without a penalty. This might just include paying the photographer standard rates for the time wasted or a call or visit from their company lawyer, etc.
This is business all the same so do not take it lightly.