Cycling new tank

Hi guys, just getting back into marines and have gone out and purchased a tank (reefmax)

also purchased....

power heads

heater

RO system

Salt

sand



my question is.... can i start a cycle without live rock? or is this a must?

I wanted to fill the tank tonight and get it started but wasn't sure if it was worth doing without the live rock.

If it is ok to start now, what side effects will i have once i do add the live rock?

any info would be great.

thanks guys.