That’s already enough time to create your art piece, I hope there will be no extension since it will be unfair to those who submitted their art work in time. If you are is already available, better to submit it now so you can have the advantage of being the first and unique art. Anyway, you still have time to prepare for it and make it perfect, I expect more participants for this round, the competition is getting tougher.
A month of work for creating an art must be enough already but for those who are late to see the thread, they only have a limited amount of time left and it could affect the quality of their art works but they are lucky if the team will give them an extension. Those who are early must not worry because maybe those art who submitted late will have a resemblance with the other art works or in other words it will not be totally unique anymore (like you said).
Contests like this from Roobet are not really new and many people have waited and prepared their new talent for this. That makes the competition bigger than ever but isn't it more challenging?