Agree with JSD24. It is very state specific, so I would get a copy of your state's special education policies, parents' guide, etc., and see what the procedure is for in-state transfers. Usually, the new school district has to either accept the evaluation and IEP from the previous school district and therefore implement the IEP as is, OR the new school district can reject it, in which case it would do it's own evaluation and determine eligibility or draft a new IEP. If the latter, the new school district has to keep the "old" IEP in place and implement until they either exit the student from special education (not likely in this scenario) or develop a new IEP document.
I think what you are doing is the correct approach. If I were you, I would prefer an IEP that is as specific as possible before a transfer occurs. I would also reach out to the new school for a meeting to discuss issues like tardiness and absences and how they are related to her disabilities, so you can know upfront how they will handle this rather than being blindsided when an incident actually occurs.