By my reading:
Casting Time 1 round, so the spell doesn't go off until immediately before your next turn. Pretty straightforward.
Next round, just before your turn comes up, the spell completes and you may take an unarmed full attack or flurry of blows as if you had taken a full attack action. I agree it's poorly worded, but the example in the text makes it pretty clear.
Basically, you spend a turn charging up (without actually losing a turn, just going really slowly that turn) and then make your unarmed full attack or flurry of blows at a range. Note that you have to deal damage (half fire and half sort-of-negative-energy), you can't replace these with trips or disarms or sunders, etc.
I'm having a lot of trouble imagining a situation outside of a 'gestalt' campaign where this spell would be particularly useful, but maybe there's a cleric archetype somewhere I missed that gains a monk's flurry of blows and unarmed damage progression, or (more likely, imo) a monk archetype that gains the ability to cast a limited number of cleric spells and thus could use this spell to deliver their flurry at a range.
Had I written this spell, I'd have made these changes:
Duration: One unarmed full attack or unarmed flurry of blows (see text)
Your unarmed strikes release blasts of energy in the form of bolts of fire or glowing red crows, which fly instantaneously to strike your target. Upon completion of this spell, you may immediately make a number of unarmed strikes exactly as if you had taken a full-attack action, including your flurry of blows class feature (if you have one), against a single creature within Medium range (100 ft + 10 ft/level). Your attack bonus for these attacks work exactly as they would for a normal unarmed full-attack action or flurry of blows, but the damage for these attacks are half fire and half negative energy (this negative energy damage does not heal undead). You may not substitute or augment these attacks with combat maneuvers or special attacks (such as Stunning Fist). For example... (example from text about a 14th level monk continues here).
It's important that you don't lose a turn when casting this spell. Your attack doesn't happen until just before your next turn, but immediately after the spell goes off and you make a full attack it becomes your turn again. It's also important to note that while casting the spell provokes attacks of opportunity normally, the "ranged" attacks granted by the spell are not ranged and do not provoke attacks of opportunity unless your normal unarmed strikes would do so.