@VanGoSunflowers
Us two and @SpanielsGalore are all going to end up living down that rabbit hole, but I'm working on the theory that this might be of interest to other puppy people... maybe...?
With the Calibra it's significant that the Junior lamb has different nutrient levels in small/ medium than in large/giant.
Small is 28% protein, 18% fat, 1.6% calcium, whereas large is the same protein level, but 15% fat and 1.3% calcium.
So it's not just the kibble size that's different.
In theory, you could go either way for Pablo, a Labrador is technically a medium breed, but arguably some would refer to a male as large. I'm not a breed expert so I can't say which is more appropriate for him, though given their predisposition to skeletal issues I'd lean towards large.
I would say that once Pablo reaches a year, you can start introducing some adult food although as you know, @LandSharksAnonymous does not recommend it, so it's very much personal choice.
Don't feel you have to stick with the Calibra though - there are a lot more options out there for you than there are for me, it was just that I struggled to find a large breed junior lamb. As I discovered with Millies Wolfheart, a giant really does need specific large breed formula. And I know, you'd think I would have cracked this by now, 8 dogs in, but apparently not. There is always more to learn.