All the above advice is true info.
But to answer the Original Poster's question -
Seven layers of equal thickness, of metals that weld together well ....is a good starting and learning billet.
Once one has done a few of these, they can easily move to billets with different thickness layers, higher layer count, complex materials, etc.
What I was getting at in my explainations is that even though a good damascus maker with a power hammer/press can weld up a 6" stack of 40 layers, that doesn't make such a billet a good learning tool for hand forging (Unless you want to learn to fail).
Moderators note:
It is a regular issue on these forums that a person will post a question and some advice will be issued. Then others will come in and post questions to that answer. Soon the thread is more about those questions than the OPs need for advice. Often ,the reason for the question gets lost in the discussions.
If there is a question about some posted procedure or other issue, sending a PM or email is a better way to get your answer than side tracking a thread.
This particular thread was not so bad, but in some cases, a reader could never guess the original question by the last twenty posts.