This is from the destructions on Wyeast's web site:
3. Allow the package to incubate and swell for 3 hours or more (it is not necessary for this package to fully swell before use) at 70-75°F (21-24°C).
And also this:
Full swelling of Activator™ packages is not required for their use. The contents of Activator™ packages may be direct-pitched without prior activation. Our smack pack technology is intended to be a tool for your use in determining viability, and in initiating metabolism for faster starts to fermentation.
Sterile Packaged Product – UV Light Barrier – 100% Guaranteed Pure
Keep Refrigerated. Do not freeze.
Best if Used by: This package is best when used within 6 months of the manufacturer’s date when stored between 34-40°F (1-4°C). Older yeast or yeast that has been exposed to higher or lower temperatures may take longer to become active or swell.
Wait longer if you have the time, if not, i would pitch it.