A lease is a legally binding contract and generally can not be changed verbally.  So any "agreement" that the landlord wanted to move the date as listed in the lease should have been done in writing.  And you should have been given "consideration" for the change in the agreement, generally speaking an "abatement" or reduction in the rent for the 2 months that you paid while the premises were completed.  If you choose to you can indeed press the issue and I believe that you will be successful.  I would, however, do so cautiously as you have to deal with the landlord for the next 10 or so months.  Do not ignore your rights but assets them sugar covered.  Good luck.