Hmmm. If it's only a pullout, then I will add more. First grade can be dreadfully horrible for kids who already know how to read and do basic math, as that is usually what they teach in first. Can you volunteer or otherwise go observe in the classroom to get a feel for what's going on?
The GT teacher may be a helpful advocate too. Maybe you can ask the GT teacher if there is additional stuff going on in the classroom for the GT kids (e.g., differentiation, clustering).
As for how long to wait for the teacher to get to know your kiddo, that depends on what type of kid you have. Mine would have hidden his abilities to blend in. He doesn't like to stand out and does not like to speak in class. So the teacher wouldn't have know about his abilities until much later. Also depends on how much your kiddo is complaining.
If he complains every day, that's a big problem and I'd want to meet with the teacher sooner rather than later.
When/if you meet with the teacher, you will want specific examples of why you think your kiddo might need some more challenging work. E.g., what sort of math have you seen him doing, what books is he reading. Is he allowed to pick out his own books for free reading? Check out the classroom library, too -- if there's nothing at his level, ask the teacher if she minds if you donate some books.
These are just random ideas, as you haven't yet described in particular you would like. Before you meet with the teacher, have a clear view of what exactly you are hoping for. Can you give more details about what you'd like here? Then we can try to help you brainstorm. Lots of us have been there/done that. (In our story, we ended up getting a grade skip for our DS, using the Iowa Acceleration Scales to give the school objective evidence as to why the skip was a good idea.)
