Maybe something to add to the list:

Cherry Blossom season should be towards the mid/end of April.

There's no specific date as it depends on when the Cherry Blossom bloom. They are only in peak bloom for roughly a week so it's easy to easy to miss.

You can see when the cherry blossoms are in bloom from their site. I've been to the Cherry Blossom festival pre-COVID (like 8 years ago) and it was super PACKED with people and I think tickets for that festival weekend was more expensive.

Personally I hate the crowds so I much prefer going on a weekday during peak bloom week when there's not much people there. I went last year and it was lovely, there wasn't too much people. If you only have weekends off, maybe try going the weekend before or after the Cherry Festival if you want to avoid the crowds.

The only bad part about going during the week of the Cherry Blossoms festival is that you'll pretty much only see the Cherry Blossoms cause nothing is in Bloom that early so don't expect much of anything else.