when we got millie we crate trained her (shes aspringer x so med sized), she was trained to go in her crate for 'nap time' lol! etc
Her cage is 'her space' its where she feels safe and also her' time out' to reflect on things like if shes been naughty, i can say time out and shegoes straight into her cage etc - she feels safe and secure there
i put her in there from day 1, i got her very young 6 weeks, her mum was very young so had enough, she was supposed to be in there at night but iw as very naughty and let her sleep on my bed

lol!! which was fine as she just slept and felt really safe, and was dry all night from 6 weeks old!! obviously we had the accident in the day but it only took a few weeks and she was toilet trained.
feed them in there, let them sleep in there, if necessary put the crate in your room in the night, and in the kitchen in the day etc, when you go out, pup goes in the crate etc - i was fortunate as she was never in there for longer than half an hour a day - somedays never - because she came everywhere with me, still does.
mistake i made as well (alightly off topic) was using newspaper - imo it just confuses them - so thats another thing with the next pup, !!
you learn from each pup, we never used a crate before millie, it works well, the next pup will have the crate, millie uses it now rarely as she so well behaved now, thanks to a training techniqe that someon on another forum told me about, brill!
obedience - i had my millie sitting at 6 weeks, she was intested in food that i had in my hand so she just automatically sat to see me bcause she was so tiny lol!! so i enforced it by saying sit, 2 weeks later we had down perfected, then stand - shes now 1 year old and she can do distance conrtol, lots of tricks, heelwork etc - shes competing in agility this year when we have trained more, i would also like to do obedience comps too. Be persistant but make it fun!! dont do more than 5 - 10 mins a day with sucha young pup, use play as well, with a toy and make them sit, give them the toy etc - if they mess up - dosent matter my trainer just said too me go '"oh dear, no big deal! " in a happy voice and try again, no point getting annoyed with the dog dosent get anywhere - they dont understand
hope this helps
suze