Short answer is: it depends on Pennsylvania law. It might not be a bad idea to consult with a lawyer in the appropriate area of specialization to go over the rules before making a costly mistake.
Longer answer is: There are a few things you need to look at before October 1:
* Does PA law allow you to collect UI even with pension income? (In some states, it is allowable but benefits may be cut back somewhat by an offset for pension income.)
* If you can collect UI, does the severance package impact your ability to immediately qualify? In some states your severance can be used to offset what would have been paid out.
As for deferring the start of the pension, that's likely dependent on the details of the pension plan itself. There's really no substitute for professional knowledge in this case, and knowledge which specializes in PA law. Good luck!