Hi Yaroslav,
Thank you for the interest in the project!
The whole project takes 100 days for 100 masterpieces.
As now the subject is hot around this topic I will start reaching out to museums in this week and/or next week, first with museums with PD materials.
If it is possible to show the museums that they get more and more articles written on Wikipedia about them, the more existing they hopefully will be.
As you may have noticed, it is going ad-hoc, which is the result of the missing collaboration of the core organising organisation.
The first step is now getting the museums in Wikipedia. When the museums start to provide us images, we also will look to which masterpieces are notable to add as own article in Wikipedia.