I'd either do a small mash today and start the starter, or buy some DME and delay brewing. Those propagator packs are not designed to be pitched into wort- even Wyeast says not to. I think you'd have some very stressed yeast, a very long lag time, etc.
Even with the Activator pack, a starter is recommended. With a propagator pack, it's crucial.
From Wyeast's website:
Propagator packages are designed for and require a propagation step (starter culture) before brewing.
Propagator packages contain live yeast cells in a liquid slurry. This yeast slurry is packaged in an optimum condition for storage, while maintaining the ability for rapid and complete fermentation.
Propagator packages include a sterile liquid nutrient pouch that, when smacked, releases its contents into the yeast slurry and activates the package. The available nutrients initiate the cultures metabolism which in turn generates CO2 and causes swelling of the package. This process will reduce lag times by preparing the yeast for a healthy fermentation prior to inoculation. Activation also serves as a viability test of the culture. Expansion of the package is an indicator of healthy (viable and vital) yeast. Although beneficial, cultures do not need to be activated prior to inoculation.
Usage
The Propagator package contains a minimum of 25 billion cells in a yeast slurry. This volume is not adequate for direct pitching into 5 gallons of wort and requires a 1-2 L propagation step prior to brewing. The Propagator is designed, when propagated in a 1-2 liter starter culture, to inoculate 5 gallons of standard strength ale wort (1.034-1.060 SG) with professional pitching rates. For lagers, we recommend pitching the starter culture into the wort at warm temperatures (68-70°F/ 20-21°C), waiting for signs of fermentation, and then adjusting to the desired temperature. Alternatively, for pitching into cold conditions (34-58°F/ 1-14°C) or higher gravity wort, we recommend increasing this pitching rate further by performing additional propagation steps. Please see the Pitch Rate section for additional information.