I don't personally think you need to wait 6 months before getting corals. You do however need a stable system and 6 months can be the time frame for some to stabalize their system, but it's not always the case with every system. The key is to have worked out all the kinks before adding corals, and to have next to zero fluctuations in your parameters. I would aim for 1.025 for your SG
if you plan on corals.
Now don't take what I say about corals and jump in soon.... Do allow yourself the time to stabalize your tank. Corals are expensive and it's not worth the risk to jump the gun.
I would also add your clean up crew after your cycle is done and your nitrates are around 10ppm. You could stock a couple of fish shortly after the cycle and wait until your tank starts to look "lived in" before adding the clean up crew just to ensure they have something to eat.