I had a TT in June of '09 and experienced some similar symptoms, especially the trouble focusing. My surgeon didn't know what was going on so I made an appt with an Ophthalmologist. He told me that what I was experiencing was very, very common in people who had general anesthesia. He gave me some really good eye drops (almost a gel consistency) which helped. Within 2-3 weeks everything was ok with my eyes. As far as feeling foggy and dizzy...I had the same thing. I was 54 and very active and felt like I was totally out of it for at least the first week. It went away. It was simply my reaction to the whole ordeal, especially the anesthesia. Nothing immediately after the surgery was related to my thyroid hormones. I was lucky in my choice of endocrinologists. He tested me often (starting 2 weeks after surgery) and then every 4-6 weeks for quite a while until we got the meds right. He listened to how I felt in addition to the lab work. I kept records of how I felt , any funky symptoms I had etc. Whenever I had a med dosage change I wrote down daily how it was making me feel. I shared all this with my dr. I probably spoke to him every 2 weeks for at least the first few months. The bottom line is that I feel totally normal now...better than I had before the surgery. I'm also one of the lucky ones who only needs to take synthroid. Good luck.
The half life of T4 thyroid hormone is about one week. I think this means that whatever T4 is in your body at the time of TT would be about 90% gone in 4 weeks time. The T3 in your body would be gone much faster since it has a half life of less than a day. So my opinion is that you would be feeling the effect far before 4 weeks. I have no direct experience with this, so hopefully other member that do will respond as well.
Rather than just speculate about the hormone levels and their possible connection to your symptoms, why not just call and ask the doctor to do the testing before you go in for the next visit? Specifically, I would ask for free T3 and free T4 (not total T3 and total T4), and if the doctor resists, just insist on it and don't take no for an answer. They always test for TSH, so you won't have to ask. That way you would be able to walk in with a lot more info in hand and be better able to discuss your need for meds.
For your longer term needs, I also suggest that you find out if the doctor is going to be willing to treat you clinically by testing and adjusting FT3 and FT4 levels as necessary to relieve symptoms. Also find out if the doctor is willing to prescribe meds other than T4 types , if the need arises. If the answer to either is no, then you will eventually need to find a good thyroid doctor that will do so.