The dealer recommended 3500 miles for my 2014 T&C with the same engine as yours. We bought it in October, but it sat on the dealer lot for a long while bad has a 3/14 build date, so this week I took it in and got its oil changed at 1,200 miles. I asked about switching to synthetic and they said I should wait until at least 2500 but be more like 3500. So I changed it with regular oil this time around. In July when it has been 6 months and has 3000 miles on it I will switch to synthetic then change it yearly, because the van is only being drove 3,500 to 4,000 per year.
On the other hand I did my first oil change in the Durango at 3,317 and switched straight to synthetic oil, then changed it again at 11,313 4 months later. I let the dealer change the oil in both vehicles because I have the lifetime warranty on both and I don't want any issues with claims of missing scheduled maintenance and it builds a relationship with the dealer and they will be less likely to fight you if a "questionable" claim comes in.