It depends. The first question to answer is 'was proper notification completed.' The operative term is "proper" because there will often be a green card (the kind signed for certified mail) in the file for the property. But if it's signed by anyone other than the party that has/had an ownership interest in the property, proper notification hasn't happened and the clock on the redemptive period doesn't start until "proper" notification happens.
The more heirs, the more complicated this gets. The more parties involved who ALL have to be given notice, the more time and effort that will add to the cost of the process. Some attorneys won't even start the process without an upfront fee, because it gets costly quickly and many times the investor seeking to quiet the title will abandon the effort because the cost will make the property unprofitable. Many times, when you start finding heirs, they don't have any ability to pay back taxes, but they want to get paid to sign away any rights to the property - adding more cost to the process.
Call around to a few title company's or real estate attorneys and see what they say.