Episode 8 - Ends at Eren crying and saying "Dina..."
Episode 9 - Ends at "It's name is the attack titan"
Episode 10 - Ends at the ocean
Episode 8 adapts the remainder of 86 as well as more than half of 87 as seen by the preview at around 65 pages. These two chapters are some of the most dialogue dense in the manga, so there's no way they can do more than this unless they cut stuff. Episode 9 adapts the rest of 87 and all of 88 for about 65 pages of content. Episode 10 adapts all of 89 and 90 minus Ymir's backstory, but this still adds up to a massive 80 pages to adapt. So yeah, no room for filler. They might rearrange some shit or make some cuts to chapter 89/90 to make it work, but there certainly won't be filler.