We all are expecting big things from Zero, but we should not expect it to perform the way some Sallu/Aamir movies have or how Sanju has.
It takes a lot for movies to perform that way. From trust to trailers to songs to general curiosity to the most unpredictable factor - WOM.
Currently looking at the way Sanju is performing has made many expect big from Zero too. Not only on forum but I see it all over twitter and FB. Many are expecting it to perform at best-case scenario.
First of all, just remember that the trust factor isn't there. Do not forget how bad JHMS was. If you think just a little bit of time has made people forget about the epic disappointment of that movie, then think again. I have seen how the attitude towards SRK has changed. 2 of my best friends, both die-hard SRKians have not even dared to watch JHMS because of how toxic the WOM is, their spirit is broken. Other general fans do not have the same enthusiasm that they used to have about SRK. When people see SRK with the same heroine again in a romance movie their first reaction won't exactly be warm.
Secondly, Aanand L Rai might have some popularity on social media, but in the real world, he is practically unknown. He has had 2 HITs so far, both below even 0.75cr footfalls, and one Blockbuster which had less footfalls than SRK's semi-hit Dilwale. He is not the known quantity that SLB or Hirani are. So don't think he'll supplement the lack of trust. And do not forget that he has actually directed 5 movies, 2 of which were completely forgotten disasters, so he doesn't exactly have the Midas Touch. He is also making a crazy jump from 39cr budget to 150cr+ budget. That can be a lot to handle. His big weight loss might give us an idea of what the stress has done to him.
Thirdly, if you're thinking that the director's previous success is an indicator of what will happen with Zero, then remember Rohit Shetty had a Super-Hit before Dilwale and a Blockbuster after. It was the SRK Christmas release that was dislike by the audience.
Speaking of Rohit Shetty, he is making a movie produced by SRK's best friend that will come a week later. If that movie gets WOM like Golmaal Again, that'll make life tough for Zero.
There are many things that can go right for Zero, but even more things that can go wrong. Having a positive attitude about the movie is good, but please don't go setting expectations so high that you end up disappointed.
All I'm hoping for is that SRK finally gets a HIT. Even Lagaan and Wanted were only HITs, but the impact they had on Aamir and Sallu's career was massive. Right now he needs that movie that makes the audience talk after watching it, the movie that makes the audience excited about whats coming next, the 3 Idiots/Dabangg will come later.