It took the Earth 4.5 billion years to form.
Listen, many of us here know you can speak English and can see what we are doing here. We know you are visiting and hanging out in the oceans and what not.
How about doing some flyovers of populated areas again like over Phoenix back in 1997. Hang low, make sure visibility is high, make SURE people have their cameras out and are taking video and pictures. I know your craft have the ability to monitor far more than just heat signatures.
So, go ahead. Let er rip!