A lot of people are saying pain might back off etc if madara says the 8tails have escaped because they have to do it in order, however in shippuuden when deidara brings gaara, the 1tail to extract, they mention how they have done other beasts already, and there are 2 other eyes open on that statue from other jinchuriki, also itachi and kisame went after naruto before many of them were sealed.

Naruto can be sealed whenever, the evidence suggests they never had to, and never have, sealed them in order