The answer is sooneest
"Soon" is an adverb. Its comparative and superlative forms are sooner and soonest.
most soonest
Soonest
sooner and more soon
sooner, soonest
sooner, soonest
The superlative form of "movingly" is "most movingly."
The superlative form of clean is "cleanest".
The superlative form of clean is "cleanest".
The superlative form of ancient is ancientosity
soon-sooner-the soonest
Comparative sooner Superlative soonest
comparative - merrier superlative - merriest
"Poke" is a verb and a noun and, as such, does not have a superlative form.