Frame deletion question

[SMewtwo]

How do I delete frames preceding a frame? Suppose I have a animation with 50 frames and I want the animation to start at frame 30. How do I get rid of the previous frames without messing up the later frames?

 

[GP&B]

I believe how you're supposed to handle it is not delete frame 1 ever, but frame 2 instead. If there's a disconnect animation-wise between frames 1 and 2 after deleting multiple frames, just copy frame one over into frame 2 and do whatever adjustments you need to fix it.