Someone named Jim PM'd me through GW, but they don't pass along your email, so I'm answering here.

You asked:
"I notice you bolted a 2x6 or so, to a concrete pad, and attached your stringer to the 2x6. Did you install those bolts after your pad was poured? If so, what did you use and would you say, concrete that has been cured for 6 days or so, is [easy] to drill into?"

First of all, I used a a 2x6 that was PT for ground contact (important!), and I drilled holes in the concrete a few weeks after it was poured with a hammer drill. Easy peasy. I've hammed-drilled anchor bolt holes in much older concrete as well, with no problem. The key is to use the right tool. :-)