Adding DME at secondary

I've just moved my all-grain Dead Guy Ale clone into secondary in a glass carboy, but the O.G was too low initially. Therefore, I boiled and cooled two pounds of Muntons Light DME, added it to secondary first, then siphoned the beer over. So far there hasn't been much activity (was done around 7PM on Oct. 6).

Usually, how long does it take for fermentation activity to show up in secondary? I know the usual rule is 18 hours for primary, but does it apply here as well? Also, will the DME alter the flavor significantly? I made sure the DME didn't caramelize, but hopefully two pounds added to a five gallon batch will ensure full attenuation.

You racked it off the yeast, so the fermentation will be really slow. If you think about it, a typical carbonation time for bottles is two weeks and that is with only 4-5 ounces of corn sugar.

I don't think the flavor will change.

I'd re-pitch. Any dry yeast would do.

Well dang, I used the Wyeast Pacman smack pack, if I repitch then I'm thinking of using another of the same yeast, though any recommendations for an alternative are welcome.

I'm planning on having this sit for at least three weeks, so even if I don't repitch will it still fully attenuate by that time?