At the Termination of Previous Job
Check your pension plan
The Federal Government has some regulations regarding who can transfer previous pension eligibility into their pension plan (as pensionable service).
One aspect is the length of time between previous employment and government employment.
Another factor is when you decided to become a federal government employee.
You can stake a claim by applying, immediately upon being laid off, for any federal government position for which you are reasonably qualified, and documenting the application (e.g., printing the web page, saving the confirmation email, etc.).
Then, should you actually end up working for the federal government, you have a good claim for being allowed to buy into their pension plan.