I usually put alfalfa down at least 3 times a year, 4 if I'm not behind and forget. There's a holiday schedule that some use but I can't remember how it goes. Since most of my beds are redone each fall I add alfalfa pellets to the beds and till in (November). It's usually a couple to a few weeks before I get to plant everything back in the beds and I will add a handful to the planting holes, backfill a little with soil, add a little more alfalfa around the plant, finish filling in and then I will go back once the bed is complete and pour alfalfa in between the rows of daylilies.
Then in February I will pour more in between the rows of plants to give them a boost since we should have blooms beginning in March (April if the weather is cooler) and then again in May I will add more to the beds. If I have time and don't forget I will add more in late August.