We like to keep our cigars at between 65% - 68% humidity (though 65 - 72% is fine).
The seasoning process can initially take 7 - 10 days and a full bottle of solution in our hydro tray to reach 65%. After adding cigars, it's likely the humidity will drop 10 - 15% or so. You'll need an additional bottle of solution and another 2 - 3 weeks to re-stabilize at 65% - 68%. This isn't because the box isn't holding humidity, but it's because the cigars are absorbing the moisture, and humidity likes to stay at the bottom of the box so it takes time for the humidity to rise enough to be caught by the sensor.
If you live in a very dry state - southern California, Nevada, Arizona, etc, or during the winter you can expect to have to add WINTER SOLUTION more often to the hydro tray. These states can hover around 30% humidity so you will be constantly fighting dry conditions. It won't be uncommon to have to maintain your humidor by refilling the tray weekly or even more often.
In more moist states during the summer, you may only have to refill your hydro tray with humidor solution once or twice a month after the box has been thoroughly seasoned. During the winter months, it's likely your box will need more maintenance as it tends to be much dryer during the winter.