You did not state how long of a delay there would be. I would suspect that if it was a short delay - a few days or so, then it would not be considered a material breach. Every "breach" is not a grounds to avoid a contract if the breach is not material.
This is not intended to create an attorney client relationship and none is to be implied either. You must contact an attorney and present all facts before you can and should act on this response
To answer a contract question, an attorney needs to see the contract. Without knowing anything about the contract, In most contracts, this fact scenario is not sufficient to constitute a breach.
Whether or not the delay in move-in is grounds for terminating the lease depends on what the lease says about a delay to start. For a definitive answer to your question, you would need to show your lease to an attorney.
I hope this information helps answer your question(s).
~ Kem Eyo
The above answer is a general explanation of legal rights and procedures. It does not constitute legal advice. Nor does it establish an attorney-client relationship between the individual posting the question and the attorney providing the answer.