Those baby plants are called bulbils and they can be used to start new, independent plants. I have no experience with this species but I will offer some general pointers based on my experience with others. I welcome anyone else who has experience with this species (or any other agave bulbils) to speak up.
Usually it's best to wait until after flowering is complete (ie. the top-most flowers on the stalk are done) before harvesting bulbils. They will get bigger and bigger on the stalk (though not by a whole lot, given the numbers) and so you benefit from waiting a bit before you grab them. Bigger to start with is better, because it gives them a bigger reservoir of water and nutrients to subsist on until they can grow roots and obtain water/nutrients for themselves.
With some plants there is a sort of auto-release mechanism. If you shake the stalk, bulbils will fly off when they are ready. You can try this when they look ready, otherwise just separate them carefully and pot them up to grow roots. This process will take weeks to months.
If you are harvesting dozens, start with a nursery flat or some other wide, shallow container. If you are potting them up individually, don't go crazy with big pots at the very beginning. They will tend to look sadder and sadder as they dehydrate, and then visibly turn the corner when they have roots and can take up water again. Use containers with holes and soil with good drainage (like 50% pumice/perlite/gritty equivalent). Water like you would any other potted agave, ie. watering well when the soil has gone dry or almost dry at depth. Provide strong light but maybe avoid direct overhead sun while the bulbils are small and rootless. Once they have roots and look rehydrated, you can freely pot them up into a bigger size.
Hope this helps. This method should be relatively reliable (maybe not 100%, but you have no shortage of bulbils to experiment with). However, you have to be patient while they root.
