While most cherry blossom trees in Tokyo bloom towards the end of March and into early April. There is a variety known as Kawatsu-sakura (河津桜) that bloom much earlier. It’s difficult to find a single location with many of the trees but one such place exists about an hour and half south of Tokyo in the Miura Peninsula near a Miura-Kalgan (三浦海岸）station. A visit in late February is usually pretty safe for nice flowers.
The city was administering a page this year (2016) but if that link doesn’t work a quick search should reveal somewhat regular photos.
The Kawatsu Sakura tends to be a lot more pink that the Someiyoshino (?) variety that is seen more commonly. Oftentimes the pink is juxtaposed with the yellow of ”Rape Blossoms” (What a terrible term for a flower) for a nice contrast.