Hi Pa&Ma,
I think almost every hospital will give diaper bag when u deliver there, but it is very basic one, not pretty kind lah
Anyway, if u r contemplating, i think u can wait till baby is born.
Those hospital gift diaper bag can be use temporary, meanwhile u see whether u need it or not.
As for me, I used regular backpack, some brand like deuter.
To make it organized, i use ziplock bag.
One bag for fresh diaper, one bag for changing mat, diaper cream, wet wipes, one bag for clean clothes, hanky, etc.
I found it easier when i wanna look for something.
Hope that helps.