It depends on how “fast” the blossom progresses as well as the weather conditions after full bloom (wind and rain can strip petals from the trees but a cold spell can prolong the season)

Last year was a particularly early and “fast”year.
2018 - Tokyo
First bloom (first unfurling of the buds) came at about 18th March.
Full bloom was around the 26th March
By the end of the 31st March, despite no major wind or rain, most of the Sakura was gone.

The prediction at the moment is that the Sakura progression won’t be as “fast” or come as early as last year, but it will be “faster” and earlier than the average.

As a comparison, 2016 was the opposite. A cold front came at first bloom time and prolonged the season.
2016 - Tokyo
First bloom - around 24th March
Full bloom - 1st April (it was gorgeous for a few days before this)
Full bloom was over by about the 8th, but mostly because of strong wind and rain on the 9th & 10th April. Without the inclement weather it may have continued for a couple more days.