How long should it take for a plant to grow fully.

just wondering first time grower how long should a unknown seed take to grow it is already 8 inches and is 12 days old but stretched for the light but it was time for it to go into a bigger pot and i kind of like re-burried it to support it and it is 3 inches off the ground so it can stand up on its own?

Well the fact that its an unknown seed doesnt help. And to grow fully? depends how big you want it to get. depends on the size of your pots, depends on a LOT more info bro

Whenever you decide to put it into flowering at 12/12 (half of each day in total darkness) you can expect it to take probably 10 weeks before you can harvest. 95% of all strains finish with 10-12 weeks of flowering.

ok thanks and how big should it be before going into flowering.

as big as you want it, just be aware that it can DOUBLE in size or more during flowering

Some Sativa's can reach 30' tall.

Most are much less, but you can see how your question is kinda open ended.

Wet