Yes in a standard game, you'll have more than you need in air to put some shards and to cast the final skyblitz around tour 5/6 (edit: I play with 6 dansefly, I don't know
how it works with 5 /edit)
But I don't like the idea of using the minor phoenix/ cremation combo in agressive decks, because your phoenix is ash for two attacks phases and deals 0 instead of 8 (or probably 12 with crit shots) damages, and you'll need more than just a cremation to cast the seraph...