IMO, its better to start with the sand and rock now so you dont a cycle later and possibly kill your fish.
Its been almost four years since our 75 has been setup and I started like you did, My advice to you is dont rush you will end up very frustrated.
I started with a 75 gallon tank, 2 emporer filters and a cheap skimmer sand and live rock, Now I just have the 75,sand and live rock and a Octopus skimmer,The live rock will do the filtering for you if you have enough and do your homework it will cost you less in the long run... Now I have a bunch of useless equipment and wishing I would have listened to the seasoned reefers... For the lighting I have a t5 unit and Im very happy with it.