Thanks, Alex.
Note that 1st train to Guangzhou leaves at 7:13 - impossible to make by public transportation, unless, perhaps, you happen to live in Chenggong.

@Alex: your Wuhan-Beijing trip - was that a high-speed rail train? I had thought that standing wasn't allowed on such trains.

Went out all the way by subway yesterday evening to South Train Station to see just how long it would take. If I'd taken the earliest morning direct subway train and if it took the same amount of time, I would arrive at 7:32, leaving me 21 minutes to get on the train at 7:53. Was told at the station that one needed to arrive for trains 20 minutes before departure. Perhaps that could be ignored, but given that the ticket gates usually close about 5 minutes before train departure, that's cutting it pretty damn close - as somebody wrote above, the place really is huge. A staff person at the station suggested I might take a room in a local hotel in the area the night before in order to make the train in the morning.
Station is fine, trains are fine, but it seems coordination between subway schedule and early-morning train schedule is not quite as good as it should be - and I note the bus schedule mentioned elsewhere puts the first bus leaving Kunming (I mean the real Kunming, not Chenggong etc.) at 7AM, which is way too late.
Was also told by same official that if I missed the train I could use my ticket for the next train, which is quite a bit later - but then aren't all the seats reserved ones, and most/all reserved in advance?

I note the bus schedule mentioned above puts the first bus leaving Kunming (I mean the real Kunming, not Chenggong etc.) at 7AM, which is way too late for, at least, the 7:53 train to Guangzhou. Perhaps a little more coordination might be in order?

@bilingual: agree with you - too much emphasis on form and niceties (not necessarily bad, taken in itself) rather than on content and fundamentals. But we are indeed having very weird weather, so I'm not criticizing the present situation too strongly.