You can start adding some corals, typically listed as easy or beginner, basically when your cycle is over. Do not get your absolute favorite piece right off the bat, get something simple to get the feel for everything. You of course want to start everything towards the bottom of your tank to acclimate to your system, after acclimation you can choose the placement for the coral.
You want to have a good idea of what corals you will want in the long run, and reserve the space the desired corals will need. For example, if you want sps coral later but you start out its a coupe mushrooms and a Zoa frag, do not place them in your high light areas rather save the high light areas for your later sps. If you want sps, you need to be sure your system is fully established and stable, 6 months to a year, again start them on the bottom but you will want to put most high. When placing sps, consider the growth pattern before placement. For example do not place a capricornis above a strawberry shortcake, because the capricornis will eventually shade out the strawberry shortcake. When dealing with LPS, you need to consider which ones are aggressive and leave appropriate space for growth and sweeper tentacles. Hope I helped.