First off I will say that every puppy is different and I think you need to work with what you have...
That said, Rainah has been staying in her crate during the day for 7.5 continuous hours since she was 5 months. (I've read everywhere that it should be however old in months they are plus 1 month, so a 5 month old would be 6 hours max, but obviously this doesn't apply to every dog) She has never had an accident and doesn't make a sound (the first time I tried her for that long I stayed home to see how she would react)
We got Rainah when she was 10 weeks old and she was sleeping right through the night about 2-3 weeks later. (from about 10 PM - 6AM) Every now and then she will wake us in the middle of the night, but its rare. Lately because its been so hot we let her drink water all through the evening and so she sometimes needs to pee in the middle of the night.
Anyways, I wish you the best of luck... keep with it, they learn quickly
PS - Exercise exercise exercise... I think part of the reason Rainah does so well in her crate during the day is because we walk her for about 1.5 hours first thing in the morning and then she has about another 2 hours hanging out around the house before she is put in her crate....