Not staggered during first punch, but after he was hit. Do you know what I mean by he got “combo’ed”? Have you played any fighting game? Do you know what happens when you are in a combo?
The 3 air pressure punches that hit Madara, can be considered a combo, their long last effect exist at once, together with the first one.
Madara reacts easily and forms a shield in time, when Gai comes directly at him with no other influencing factors, multiple times.