OK. Here's how to do it: First, forget about baking the particles. This way works for sure (I just tested it!)
set the timeline for a 200 frame animation
create a particle emitter
select the emitter
In the attribute editor, look under the basic emitter attributes and keyframe the RATE(Particles/sec) set it to 300
Under the Particleshape node (the tab next to the one that says EMITTER1), look under the General Control attributes and keyframe the CONSERVE attribute at 1.
Move the time slider to frame 100
Set a key for the RATE again. Leave the value at 300
set a key for the Conserve attribute again. Leave the value at 1.
Move the time slider to frame 101
Set a key for the RATE again. Set the value to 0.
Set a key for the Conserve attribure again. Set the value to 0.
Play the animation!
The emitter will emit 300 particles per second for the first 100 frames then it will turn off. When the Conserve attribute switches to 0, the particles will stop dead in their tracks.
I hope this is what you were looking for.