Actually, it wouldn't be wrong to make predictions now even though it still looks quite early and no league has started yet because in the Champions League there will also be elite teams who will enter the European League next season. However, from the names of several teams that you have mentioned, you can actually give a little idea that next season's European League will still be a league that is quite fierce in terms of competition, so there will also be quite a lot of spectators.
Predictions is something that can be done anytime provided the fixture for the games are out, you can make predictions on any of the fixtures and wait till the kick off. The fact that it's quite early may only affect the chances of winning such predictions because a whole lot can change between now annd the day of the fixture. The interest in the Europa League is very likely to higher this season and that isn't contested but I hope they deliver as expected and make it worth the while.