Two weeks in Japan for the first time

Hi guys I’m travelling to Japan for the first time in October. So far I have booked my flights but no accommodation. I fly into Osaka and then 14 days later fly out from Tokyo. So far I have planned to stay in Osaka, Kyoto and Tokyo, but I’m unsure of how many nights I should stay in each city. How many nights do you guys reckon is a good amount of time for each city, and/or is there any other cities I should go, either to stay or for a day trip?