Right. This is going to be a biggy, get sitting comfortably!
We have a 6 month old labradoodle puppy, and I'm very pleased with him. I'm not going to talk about which breeder I got him from here, but if anyone can explain PMing to me I can do it that way.
I would start looking immediately. I think I first contacted our breeders a year before we were ready to get one, and although they took the piss a bit, I'm glad we had all that time. Even with all that time, there were only 2 dogs in the litter left for us to choose from.
Even if you're not ready yet, you can speak to breeders and see if they've sold any in your area who you might be able to meet, and also contact the Labradoodle Org site to see if anyone has a doodle nearby you could meet. There are 100s of people who call themselves labradoodle breeders, but to be honest only a handful of them are worth considering, and pretty quickly the same names will start coming up.
First of all it would definitely be good to know why you want a doodle? If you want a gentle, biddable, hypoallergenic, non-shedding dog, er, think again!
The coat question comes up again and again. One of the reasons we got one is because my husband is slightly allergic, although nothing life threatening. I always maintained (And still do), that if the pup develops a coat that makes him sneeze, he'll just have to take a lot of antihystamine. Be VERY CAUTIOUS of any breeder who tells you their dogs are allergen free. They might be, they might not be. UNtil they have their adult coat you may not know, and its a very irresponsible way to sell a dog. Ours is not the beautiful fleecy type, but a scuffier coat. He seems to be hypoallergenic to my DH at least, but he is currently moulting, quite a lot.
The temperament thing was a big one for us - I know breed generalisations only work so far, but I wanted a reasonably large, athletic, intelligent dog. I don't like the heavy, show breed style labradors as much as working stock, so ours comes from a working lab line. In fact the breeder works their doodles as well. That means they are HYPER intelligent, and do need a lot of training, possibly more than I'm giving at the moment.
They seem to also tend to be very very friendly dogs, to the point where I currently have absolutely no idea how to stop mine going beserk wanting to play with any other dogs or people he sees. Treats and toys just don't cut it!
On the plus side, ours is quite mellow in the house, affectionate, and not remotely defensive or aggressive. I can happily take bones away from him, pick up bits of kibble from his food bowl while he's eating without any more reaction than a wagging tail, he's never really barked at people coming in (crap guard dog!), and has never ever shown any aggression to another person or dog. We socialiased the arse of him, and he took it all in his stride - cities, public transport, shops, pubs, crowds, you name it.
Other things I wasn't aware of before getting our doodle - they are big dogs, and over exercise is a major cause of joint problems. I don't think we were quite prepared for how long their walking is heavily restricted. They are also very 'lab' like in their eating everything, so think about what's in your garden etc. Are you prepared to fish another dog's poo out of your puppy's mouth? Because you'll probably have to!
When looking for a breeder: get recommendations, don't be frightened of breeders asking you lots of questions or recommending pre-puppy classes, make sure you can see definitely mum with pups, ideally sire as well (but sometimes not possible if stud dogs used). Definitely see the original copies of hip & eye certificates.
Think about other issues that aren't so black and white: some breeders ask for deposits for viewings - I personally disagree with this as I think it puts pressure on to buy, others use it to prevent time wasters. Some breeders keep the dogs in the house, ours didn't, as I planned to have quite an 'outside' dog I was happy with that. It possibly lengthened toilet training slightly, but not significantly. (And the dog is now fully installed on our sofa...!)
Some breeders ask you to sign something that says you won't breed from them - again ours didn't. Do NOT get a neuteured young pup (they're big dogs that take a while to mature, our breeder recommended hanging on til 12-18 mnths before getting the snip). Obviously check they're all up to date on the jabs and worming.
Hope that all helps, there's probably loads more I havent thought of yet.. but that's plenty for now!