The cherry blossoms had already started to fall by this time last year.
この場合、次のような言い方ができますよ。
ーThe cherry blossoms had already started to fall by this time last year.
「桜は去年の今頃は散り始めていた」
cherry blossoms「桜・桜の花」
to start to fall「散り始める」
by this time last year「去年の今頃」
ご参考まで！
カナダ 
