Compared to most Marvel storylines, 1602’s read order is quite easy. The main series contained many flashbacks, but the order of these as they appear was important to the overall progression of the story and therefore don’t affect the read order.
There is a possible error regarding the two limited series that followed the main series. King James was implied to die in the final issue of 1602: New World #5 but went on to appear in Marvel 1602: Fantastick Four #1. As the panels relating to James’ death are said to have occurred four months after the completion of the main story in 1602: New World it can be assumed that the Marvel 1602: Fantastick Four series takes place between the 1602: New World main story and its epilogue.
1) 1602 #1