All credit to this post goes to QLD Kev, so thank him for the following information.
There are 3 pressures you can use if you are not shaking the keg for carbonation, all are based on cold kegs.
300 kpa for 24 hours
200 kpa for 3 days
80-100 kpa for 7 days (use your serving pressure)
With the first 2 after the period, you drop the pressure and vent the excess pressure from the kegs.
The majority of my kegs are done the last way, basically hook them up at serving pressure and leave them alone to mature for a week. It's easiest and I rarely touch my regs. You do need fridge space to have drinking and maturing kegs. If I'm in a hurry for a keg I use the 300kpa for 24hr method. I do find using the 24hr method the bubbles are not as good as the 7 day, but after a couple of days the bubbles do get smaller and nicer and they all end up the same.
You can also shake the keg to get the beer to absorb the co2 faster. There is a method called the Ross method on here. Same thing as the 24hr method with the co2 bubbles, you will gas the beer but after a couple more days at serving pressure the beer will get better.
Cheers
Kev