pre booking seats. Confused !!

Help !!! please confirm the following ..... I CAN pre book my seats from April 2nd for my flight on Aug 20th free of charge as I booked and had booking confirmed before Virgin change of seat policy on Dec 16th 2013.Booking was confirmed September last year .Have I also read correctly that from April 2nd the seat selection button will change to " go" on my manage my booking site

In theory, yes.

In practice, who knows. It's a brand new system and only time will tell whether it works.