High cost of energy improvements

Our building don´t have a good energy efficiency, the commissioning process indicate many ways to obtain a good energy efficiency, we are doing first the low cost way and after the high cost way, but we think that the implementation of all improvements will spend more than two years. Can we start the LEED EB process before the implementation of all improvements? In the EAp3 we can do a phasing out process because the cost involved in this case is very high, in our EAp2 case the cost is high too, can we obtain the LEED EB certification before the end of application of all energy improvement, before two or three years? Tks.