>>280408898
Having watched the second episode now, they condensed 90% of volume 1 into two episodes. If they keep a similar pace, they should be able to adapt all the way to the end of volume 6. Sakura appears at the tail end of volume 4, so probably somewhere around episode 8/9. (She's pretty prominent in the OP, though).
I'm just worried they might try going even faster to get to the end of volume 7, the pacing's kind of suffering as it is compared to the manga.