Strategic bomber attacks began in October of 1944 from the Marianas.
Kamikazes were an indication on the Japanese side that they knew the war was lost and they were simply staving off defeat and making victory as expensive as possible. They had lost the initiative by then.
A winning army does not engage in Kamikaze, and Japan was no exception. It is only after most of their planes were shot down that they engaged in kamikaze, not before.