If you want copies of the same instrument with different pre-delays, you don't need to resort to Audacity. Just use the resizing tool (fourth icon above the sampel waveform) to add a delay the beginning of the sample. To fatten the sound even more, you can slightly detune each copy of the sample by a few Hz. All of that can also be achieved with pattern effects (e.g. SDx for delays, EEx / FEx for detune) but from my understanding you want a simpler solution, and the most simple solution would be create these sample copies.