I heard there is only private sale going on now, public sale or IEO will be coming later and no specific dates yet.

if now IEO hasn't started yet it means there will be change of roadmap because I know roadmap now
Q3 2019

the longer they spend time on IEO implementation the roadmap will continue to change

Well, Q3 isn't over yet so they might be right on time by the end of September. Or may be a little late and launch IEO in the beginning of October.