Here’s a figure for the cumulative box office of the Star Wars films up till Solo:

This chart shows that for modern day films roughly 2/3 of the total box office is made in the first 10 days, and about 50% in the first 5/6 days, also explaining why it is uncertain TROS will break 1 billion, and why it is highly unlikely it will approach TLJ. TROS had a little extra boost (10-15 million) from the holidays compared to TLJ, which was released a few days earlier. After 6 days TROS is at 257 million domestic (20-25 Dec), compared to 279 million for TLJ (15-20 Dec).