The following is all tentative and is based on a very small number of known-age birds.
Here is the HY/SY pattern of S1 in Inca Doves. Note the extremely broad dusky edge on S1 and the limited rufous center.
Note the discrete rufous center to S1 on this known ASY in March below.
All photos are from March 14, 2010, and were banded by Mark Conway of Harlingen, Texas. Thanks to Mark for allowing me to observe and assist at his site.