I was having trouble being able to see if anyone had previously asked this in the search, but then when I started to make a new post!!
Btw, the answer was in here, tl;dr 始is to begin and 初 is for the first time.
However, it looks like this new feature isn’t 100% lol
Rather than posting “+1” or “Agreed”, use the Like button. Rather than taking an existing topic in a radically different direction, use Reply as a Linked Topic.