It's says here from the moment your application is received.
"The five years is counted back from the day on which the sponsorship application – as part of a complete application package – is received by Immigration, Refugees and Citizenship Canada (IRCC)."
No it doesn't. You are misreading and misunderstanding. Read again and read the entire statement. The reference to the application received is the application to sponsor the NEW spouse - NOT the original application under which the sponsor became a PR.
Here it is with key parts bolded and underlined.
A person who became a permanent resident or a Canadian citizen after being sponsored as spouse, common-law partner or conjugal partner is barred from sponsoring a spouse or partner within five years of becoming a permanent resident, even if they acquired citizenship during that period. The five years is counted back from the day on which the sponsorship application – as part of a complete application package – is received by Immigration, Refugees and Citizenship Canada (IRCC).