If someone didn't wear a tallit during morning prayers, when they put it on in the afternoon let's say, do they make a bracha? Based on my searches online the info has been rather conflicting or just plain inexistent.
One who puts on a tallit anytime during the day certainly fulfills a mitzvah and therefore makes the appropriate blessing. However, putting on a tallit at night may not fulfill a mitzvah, and therefore one does not bless. (Rema to Shulchan Aruch Orach Chaim 18:1)
There is some controversy as to the definition of 'night' in this context: does it start at the beginning or the end of twilight? Mishnah Berurah 18:7 rules that one may recite the blessing until he is certain that the twilight period has started.
If one has already prayed arvit, even if it is still daytime, one should not recite a blessing (Rema loc. cit.)