There's a lot of "it depends" for you question.
How strong is the hive, how many frames of brood, is the queen laying good pattern, what's the population and health of the bees. Is there a strong nectar flow on now, what's the weather like, etc.
Bees do like to be crowded, but when a strong nectar flow comes on they can build out very fast. You're going to have to be the judge of when to look or not. Just popping the top lid and taking a peak is no biggie, none intrusive way of checking. Pulling all the frames to check for brood and stores is more invasive. Congrats on getting the hive boxed and best of luck.
20+ years, raise my own queens, feed when needed, I treat but have not perfected varroa management yet.