Your zone isn't listed, but for most of the USA asiatic lilies are already up and fairly tall (making it difficult to dig them up and separate them without breaking off their stems - especially if they are very crowded). If that is the case for you I'd wait until Fall.

Even with small plants "no repercussions" for all of them can't be guaranteed. Though if you're inpatient (like me!) you can dig them up carefully and gently separate the bulbs from each other trying not to damage the roots or stems. (I use a gentle rinse with the hose to loosen tangled roots.) But you are taking a risk.

-Helen