What is the priority to be considered as the deadline for extension of a patent application?

Unfortunately, by publicly disclosing your prototype at the science fair before you filed a patent application, any patent application - being provisional or non-provisional - has prevented you from obtaining any foreign patent rights you may seek. In the US, however, you have one year grace period from the date of your science fair disclosure, which, of course, you have already met by filing your initial patent application. Of course, since you seem to be constantly improving your device, system, whatever, whatever you did not disclose publicly at the fair can be foreign-filed, and the one-year dates run from each patent application. So, let's say your original patent application disclosed Invention 1 which you disclosed at the science fair. You will be protected in the US but your foreign rights are gone and cannot be recaptured. You then made some design changes and filed a patent application for Invention 2. You did not say that you publicly disclosed Invention 2, so I will assume that you did not, and therefore you can obtain foreign patents for Invention 2 if you file, for example, a PCT application within one year of filing your US application for Invention 2, provided that you only claim Invention 2 because you cannot claim any foreign rights to Invention 1. The general rule for filing foreign patent application is that for each patent application for each invention, you must foreign file (PCT or within individual countries) within one year of the US filing. You said that after two (2) months from filing your patent application for Invention 1, you filed your patent application for Invention 2, and now it has been 10 months since that filing - therefore, you only have 2 months left to foreign file for Invention 2 through, for example, PCT. This deadline can be extended for 2 months, but this must be done by petition, and there is a petition fee - the petition effectively requests that the right of priority be restored.