Feedback on itinerary

Hi there,
I will be going to Japan in September for the first time. I've booked my stays already but I'm starting to wonder if the trip is too rushed. Any feedback will be greatly appreciated. Thanks in advance!

Day 1 - Arrive in tokyo late at night
Day 2 - Tsukiji fish market/Akihabara
Day 3 - Harajuku/Odaiba (is Odaiba worth going?)
Day 4 - Sensoji - travel to Gero
Day 5 - Gero - travel to Kyoto Pontocho/Nishiki market (is Nishiki market ok to go to in the afternoon?)
Day 6 - Fushimi Inarani and Kiyomizu dera and area
Day 7 - Kinkakuji and Arashiyama (I saw Kikakuji open at 9am. Does this mean the gate outside opens? I thought visitors cannot go into the shrine itself)
Day 8 - To Kibi plain - travel to Kurashiki (Is the scenery worth it in Kibi plain? I've never been a fan of bike riding)
Day 9 - To Hiroshima/Miyajima
Day 10 - Hiraoshima - travel to Himeji -Travel to Osaka
Day 12 - Nara Park
Day 13 - Osaka Dontonbori etc (is Shinsekai better at night? I heard some people say it was really empty)
Day 14 - Travel to Kiso Valley
Day 15 - Travel back to Tokyo - DisneySea
Day 16 - Travel to Nikko
Day 17 - Nikko/Tokyo (shibuya shopping)
Day 18 - Kamakura (is Enoshima worth going to? What do you do there? Would the beach be open in mid September?)
Day 19 - Ghibli studio - fly back home

Tsukiji and Odaiba are located next to each other, so you want to do them in one day.

Nishiki Market is not a morning market, so it's perfectly fine to go in the afternoon.

For Kinkakuji, yes, the outer gate opens at 9 and we are not allowed to enter the temple itself.

I think you may need 2 full days to visit both Hiroshima and Miyajima.

Dotonbori is better at night, but I don't think Shinsekai is any better at night than in the afternoon.

Disneysea is best to be visited from early morning, otherwise it may get very crowded.

Depends on what you're going to do in Odaiba. Personally you might be better off in really busy areas such as Shinjuku or Shibuya.