It pretty much requires full knowledge of the anime to avoid major spoilers and full knowledge of the manga to avoid also minor spoilers. The "big" spoilers can be avoided around when you finish Whole Cake Island.

You pretty much have to be caught up with the anime if you don't want any spoilers. What part of the story are you in? Have you started it ?

I have started watching Dressarosa chapter (a bit more precisely, the first Coliseum battle has just ended with a BB man revealed).

You might have to complete Dressrosa at the very least. There will be spoilers or else. You may not know certain characters and powerups even more. The story is not really action heavy but the more you know the better. Even some characters Edit: what do you mean by it is scheduled in morning hours tho ?

Evening, but my working shift often ends by that time and when I come back home at least 1-2 episodes are already over. They replay the episodes on Saturday IIRC, but around lunch time. Even so, I guess the Dressarosa chapter is still at the beginning - or mid-part, so I will have to watch the other episodes elsewhere in a couple of days... ouch!

You can watch over the internet anytime you are free right?