I would not worry too much about confusing the first time user with this. I'm not much more than a first timer myself. I suggest that you label the proposed field with something like, "What time was the first picture taken?"
TF is not an intuitive interface, I'm not sure that it can be given how new all of this really is. If you put yourself in the position of someone who only rides bikes, takes pix, and knows a little bit about GPS then ask yourself how many of the fields in this dialog box are self explanatory. For example, I have been using a "GMT Offset" of "-5:00:00" instead of time zone. That's because I only recently figured out that the offset field is for the picture time error. I had been thinking that you could EITHER enter the time zone or offset.
EXIF headers may or may not mean anything to a first timer. I only understood what they were this morning becauseuntil today I didn't need to know.
Please understand that I am not arguing with you, just presenting a point of view and trying to be helpful. I have found that it helps to think in terms of what the user is trying to DO, not what the field IS. Or, put another way, think Benefits not Features.
Thanks... Bob
