Yep, some are lucky and just take to it. Sundance ate dry food from the time she was four and the vet said that Science diet low calorie was the best for her... :x
Until she was diagnosed... The vet then gave us diabetic kibble but she wouldn't eat it. Desperate and not yet fully understanding FDMB and low carb needs, I bought fish Fancy Feast for her Christmas breakfast... she ate it and was off insulin in 6 days. Thank God for home testing....
Make sure you are home testing if/when you make the switch as it can drastically reduce the need for insulin.
So, you can try them on wet right away and if they take to it, great... Expect some softer poops for a week. Might happen, might not.
But if they don't take to it, try what Elizabeth has suggested... or try half and half. Some people find they have to start with a tiny bit of wet with the kibble, then every few days add more wet and take away a few kibbles... gradually increasing the wet and decreasing the kibble until it's all wet. That can take two weeks or two months... But it's so worth it. Do it at their pace and you'll be fine.
Barclay was only 5.5 months when we got him... He'd been on dry kitten food for as long as he'd been eating food. I let him have that for two days after we got home... then gave him canned... he loved it... then we tried raw and he loved that... The transition from dry to raw was about 10 days for us... He'd have gone faster but I didn't want to upset his tummy.