A fresh cut tree, depending on size, type, humidity and heat of the environment can take from a few months to a year and a half or more. I live in Georgia, and the summer here gets pretty sweltering. The tree i cut down last weekend, if left in my attic to serve as a kiln baking at 90-100° for a few months, it may be done by August. If I keep it under the house where its dry bbut cool, definitely a year or more.
A pocket knife would take you a very long time to shape and tiller the wood.
Most of the information I've gained has been from the Traditional Bowyers Bible. 4 volumes, not that expensive, and well worth the investment if you're seeking knowledge.
Welcome, btw.