Hi Pchanggeo,
I assume you have drainage holes in your saucer, can you see little white roots coming out of the holes? if so then you can transplant them.

Failing that, when they are rooted the new little leaves usually have a 'sheen' to them which is also an indication that they have roots.

Transplant into 2 inch pots, keep moist but not soaking wet and keep out of direct sunlight. When you have 3 pairs of leaves you can pinch out the growing tip, this will encourage them to grow more side shoots. - Kath:)

Follow up:
I went ahead and potted the cuttings into individual pots on June 6. I'm happy to report that I only lost 2. Other 8 cuttings are growing and some even throwing out flower buds (which I pinched off). Unfortunately, I killed the mother plant :-(. It's a learning process and a struggle to keep the humidity up here in Los Angeles. Thanks.