Suggestions

Hello,

I'm planning to travel to Japan early May and I really need suggestions for my trip. I have a few questions,

1. Is it still snowy in Niseko or is it always snowy there?
2. If I'm looking forward to see sakura, will it still bloom in May? And where is the best city to see it? (I'm traveling to Tokyo, Osaka, and Sapporo + Niseko)
3. Please check my itinerary and tell me if I got the travel order wrong and if buying a 7day JRPass will be worth it.

Day1= arriving at Haneda around 8 a.m., check in at the hotel, go around Tokyo (Tokyo Tower, Shibuya, Ginza, Ueno Park and around the city)
Day2 = full day at Disneyland
Day3 = travel to Osaka (hopefully very early around 6 a.m.) and travel around the city
Day4 = full day at Universal Studios
Day5 = travel to Niseko (will stop by Sapporo if there is enough time)
Day6 = skiing at Niseko
Day7 = Travel back Early to Haneda to catch my flight at 4 p.m.

Note: if it is not snowy at Niseko I will probably not go there anyway and will add more day in Osaka or go to Disneysea. Still not sure

Please give me advice on my route and travel schedules because I hope I can use a really early train or overnight train when I travel between cities. This is my first time traveling to Japan

Thank you