Here is a solution that closely parallels yours using select nodes for RED GREEN BLUE.
boot node selects X1 values on startup and starts 1st delay timer. After 1st delay, DONE pulse selects X2 values and starts next delay timer, etc.
An alternative is to have multiple rgb-led nodes providing different values, and only have the “correct” node send its data when it is time:
This assumes that your rgb-led node does nothing when it is not getting an UPD pulse (which is implied by the fact it has an UPD pin…).