Do you know cherry blossom forecasts available such as…
http://sakura.weathermap.jp/ (March 21st / Tokyo)
http://www.tenki.jp/sakura/expectation.html (March 23rd / Tokyo)
http://weathernews.jp/ip/info/sakura/2016/ (March 21st-26th / Tokyo)
, which tell the expected bloom date.
Once they start to bloom, they generally reach full bloom in one week time. 🙂
No one can perfectly predict the exact date but it’s going to be in two weeks and in full bloom at the end of March this year in Tokyo.
Enjoy your trip!