While most people probably don't put much thought into it, it takes a very long time to create a sleeve of any body part. This is an early picture of a leg sleeve I'll put a lot of focus on in a share and enjoy fashion.
This leg started with the Kois (there are two on the leg, though only one is visible) but there was no notion of "sleeve" at that point. There are a few others there as well, a Doll, some Celtic Knots, and Lenore. By the time the birds came along we both knew there was a full sleeve, though I'm not sure either of us anticipated just how quickly that might come about.
Sleeves usually take years to develop, what with the pain and expense involved, but this one was measured in months!