Short answer
Hold Griha Pravesh once the home is ready to live in and a traditional window falls on a day your family can gather. Many families prefer a morning, keep the moment of entry outside Rahu Kalam, and avoid the head of the household's Chandrashtama days. Find Good Times shows the windows for your new home's town.
How ChiChakra reads this
ChiChakra checks the day's Panchangam for your town, marks Rahu Kalam (one eighth of daylight, in a slot set by the weekday) and Abhijit Muhurta near local midday, and lets you compare dates. It doesn't yet apply every regional Griha Pravesh rule, so the person conducting the puja has the final word.
Choosing the day
Sort the essentials first: keys, utilities, safety checks and somewhere to sleep. No family should be left in limbo waiting for a perfect date.
Pick two or three possible dates, check each in Find Good Times, and drop any that land on the household head's Chandrashtama days.
Plan the first step inside outside Rahu Kalam. If you have to move in earlier for practical reasons, many families simply hold the ceremony later.
Good to know
Customs vary a great deal by region. Share your shortlisted dates and the town with your priest before booking caterers.