Change of Tier 2 visa to dependent visa

Hello Team,
I am currently on dependent visa and my wife is on Tier 2 work visa. We are on the 5 year path to permanent residency in UK. My question is, if I find a new job and change my visa to Tier 2 work visa and if my wife become my dependent, will I be eligible to use the period which I was on dependent visa for my PR? Or my eligibility starts from the date i get my Tier 2 work visa?

will I be eligible to use the period which I was on dependent visa for my PR?

No you will not. You cannot combine dependent visa time with main skilled worker visa time to make 5 years. You need 5 years as a dependent OR 5 years as a skilled worker main visa holder. And the same for your spouse the other way round.

Or my eligibility starts from the date i get my Tier 2 work visa?

Yes and the same if your wife switched to dependent visa.