I definitely would not approach your principal about homework in this case when you are planning on requesting another subject acceleration next year. You want to save your currency plus it is highly likely that very few of her classmates are struggling with homework. I may be wrong but I think a lot of kids, especially the GT ones are managing to complete large chunks of "homework" during the school day. That was the case with all three of my kids throughout elementary and they were all in the GT program. I have been told by a couple of teachers that mandatory and especially optional homework serve in part to keep the many kids occupied who finish "early". Generally kids who do not finish at least a little early may have an issue and end up with the full "homework" load. My oldest was in that camp, but he had dysgraphia so I did have the option of scribing certain homework or requesting modifications.
In your case, it seems simple enough to remove all the optional stuff and reduce time on some of the other assignments (i.e., reading, math games, etc.) while modifying the rest (i.e., scribing, scaffolding, etc.) By the way, your DD can always leave IXL on for the designated time without working a full 15 minutes especially if she is super ahead in math. In fact, if she works the full 15 minutes, it may look like she did way more - that was the problem with my younger DS especially. The homework can be cut down even more if you can convince your DD to do some of it at school.
Your DD has the disadvantage of skipping mid-year whereas the other kids had a 1/2 year to figure out how to handle homework. Also, consider that most first graders, especially GT ones, can write pretty quickly if not well; that's why K is so academic these days. If you make a fuss and force changes that are disagreeable to the other students/parents, it may have negative repercussions for your DD. You don't want her to get the reputation as the kid whose parents forced an acceleration but couldn't handle the work. If she is 2E, then that's different and you should pursue written accommodations instead. In my opinion, you are better off making modifications privately as your DD needs them.
