I have a flip sim emanating into my camera frustum. Most of the
sim looks great, but a section of the sim splashes in early and should
enter the frustum, say 10 frames later than it does. resimming isnt
an option. i was looking into timeshifting this, but cant find much
direction in terms of having the timeshift apply only to specific
particles ids, or a group of points I lock off at a specific frame.
The impulse to do this, i would imagine is pretty common. Any
techniques out there? reseeding is off.

if reseeding is off or if you have an id attribute than you should be able to use the timewarp sop. if you only want to do it to a group of particles, select them and delete all of the other particles, then in another stream do the opposite. timewarp the ones you want and merge the two streams back together.