should i wait?

I'd say, get it now

It's already 85% off. I'd say just buy it now and refund/re-purchase if it goes for a lower price during the summer sale.

Bandai Namco likes to do their own sale before the bigger ones so if its like earlier years they may not even have any discount on the summer sale. Id say buy now.and check if theres another game from them you might want to get (sale ends 20ish hours).

Bandai Namco is doing their sale now and it ends when the Summer Sale starts. More than likely they aren't going to participate in the Steam Summer Sale.

If you plan on playing it right away you should be fine with picking it up now.

Summer Sale would match that or be worse. Grab it now

I´d say no!
The discount is bigger if you don't buy it.

its -85% now