You ARE worrying. So to me, what you seem to be asking is "I am worrying. When do I DO something about my worries? And take some kind of action?"
My suggestion : Could take action whenever you feel like it, or could choose non-action. Then see how it serves you.
Let me give you my impressions. (I might get some of this wrong. You correct me if I am wrong, ok?)
There's two guys. One who sent you a picture. Then the other guy that YOU sent a picture to.
FIRST GUY (WHO GAVE YOU A PIX)
OTHER GUY (WHO RECEIVED YOUR PIX)
I find it interesting you use the word "attached" rather than "interested" or "attracted." You also do not state what you are looking for with that particular guy. I am guessing romance?
For example, there is a guy I mailed for about two weeks. Finally he sent a picture. I was not attached. What would be the most civil procedure. 1. Not respond. 2. Respond and say I don't feel it.
3. Lie 4. Go meet him anyway because he's terribly funny.
You haven't spent any time with this guy to form significant attachment though in 2 weeks of email. If I change the word out it becomes...
To me a combo seems best if you are seeking both friends and romance. Something like...
For example, there is a guy I mailed for about two weeks. Finally he sent a picture. I was not (interested/attracted in developing a romance with him based on his picture.)
What would be the most civil procedure:
1. Not respond
2. Respond and say I don't feel it.
4. Go meet him anyway because he's terribly funny.
"I'm not sure I'm feeling it romance wise at this time. I'm interested in growing a friendship first -- you are funny!" Then could give it more time to see if you want to move on to building romance there also or building only friendship.
But if you know the answer already and NOT interested in more friends? Only romance at this time? Just tell him "Not feeling it, I'm sorry" politely and move on. Be honest. Don't waste your time or his.
Choosing non-action in this case solves it too -- but in a shirky kind of way.
Leaving that other fellow dangling til he figures it out himself rather than just let him now straight up ASAP how you feel? It isn't "civil - courteous and polite" to avoid giving a response. That is not kind, respectful or ethical.
With the other guy I am hearing:
Could just leave it there. He said he might have spotty internet. Could wait for him to return from travel and wait for date to arrive. Non-action. Stop cranking yourself up.
"I sent him a pix. I have no response at this time, but we have a date."
I think you could be projecting YOUR typical responses on to him now that you gave him YOUR picture and the shoe is on the other foot.
You seem to be wondering if he might treat you the way you might have been tempted to treat others when you are the one who gets the picture. Is he
1. Not going to respond?
2. Respond and say he doesn't feel it?
4. Go meet you anyway but want friendship and not romance?
If you don't want to resolve your worries with non-action and just wait for the date time to arrive?
It could be simplest to just check in and go "Are we still on for Date? Are we building only friendship here? Or building friendship maybe more here? Just so I can know what to expect on date. I am looking for ____."
Then you know what you can expect on date and so does he. Or you can cancel the date politely because it's not looking like a match up and it gives you both the chance to bow out politely now rather than later.
Up to you how you want to proceed with this other guy.
But in general? If you want to relate to people with "most civil behavior" you could be more up front honest in your relating and expect yourself to behave in courteous/polite ways consistently. No matter which side of the picture sharing you are on.