I believe the Red Hair Pirates will make their debut end of wano-entering just before the next arc. We've seen shanks viewing luffys 1.5 billion bounty poster and his so called status as a "big pirate" /"5th yonkou". Hence , their promised time to meet has arrived. Instead of Luffy finding Shanks, i reckon Shanks might be reckless/too excited and come to wano or meet him nearby on the seas. It'd be so cool to see a shanks entering the sunny scene (similar to the shanks entering whitebeards ship scene) :OWill they intervene in this war or will straw hats meet them in elbaf.
Also considering blackbeard will play a huge role will shanks interfere yet again ?