Recaps it is. Thanks.- No but the show does launch directly from where the Cartoon "Rebels" ended. Rebels is definitely a tougher watch since it was squarely targeted toward tweens and younger audiences (i couldn't do it) , so it might make sense to find a recap video on youtube somewhere and just go from there.
I've watched maybe 2 and half seasons of Rebels. I forgot what happened in it since it was so long ago. So no, doesn't matter if you go into Ahsoka totally cold. The first three episodes, maybe sip coffee in your bid to stay awake and attentive. Then the story picks up really well and you will be hooked.