When did stamp collecting start?

Answer 1

Probably in 1841 when the first variant of the first stamp (the "Penny Black") was relaesed. Other countries caught on quickly to the concept of pre-paid postage and introduced their own stamps, so stamp collecting certainly began in the 1840's.

Answer 2

Great Britain, mostly because that is where the first stamps were issued.

Answer 3

Since stamps first came out in 1850.