Here's some proof that they're all up and running in China.

On the 27th and 28th the network difficulty basically doubled.
The value of the coin has gone up, but if every batch ramps up this quickly - you can expect to see ROI get halved ... and then halved again.
If you were following profitability on a daily scale, you likely noticed that it went from about $200 per day to about $150 today. By the time they reach consumers, it'll likely be closer to $100 per day (if not lower).
The same holds true for SIA.
As for the May holiday - that's Tuesday of this upcoming week. It's essentially Chinese Labour day. If they're true to their word - they would ship between now and Monday. Something tells me that we might see some further delays.