For hospital, gender can be seen during the 20w anatomy scan. For me the gynae would ask if i want to know the gender, which i said yes then she will scan and show the genital. However if you wish to not know or either one to know you will need to inform the gynae before the scan so they wont accidentally spill the gender.
And also, nothing is too much you can do whatever you want and recording reaction would be nice to look at.