Thanks for joining CycloCamping Forum.
First, I would suggest you consider whether or not you are restricted to 1 year. Because if you're not, there is a good chance that you won't follow your original plan and you will find out pretty quickly that you're not where you planned to be at the time you planned to.
If the one-year time limit is strict, then you probably should plan it well. Before trying to get the best weather everywhere, make sure you avoid the worst weather.
On your route, the most important in my opinion is to avoid the northern part of Pakistan during the winter (Dec. Jan, Feb.). The Anatolian plateau in Turkey can also have tough winters, too (a lot of snow depending on where you are). I would also avoid the Iranian desert in the middle of the summer. After that, you should be pretty good.
So, the plan you are describing sounds really good to me. Yes, October to April is by far the best season in India. And you do want to be in India during the best season because it can get pretty miserable otherwise (rainy, humid and hot). I would not worry too much about Europe in the summer. Yes, days can get hot (but nothing unbearable) and in the end you will be happy for the rest of your journey.
Great journey you're planning, congrats!
Happy wind in Iran!