Personally I smoke aged Stonehaven in any newly acquired unsmoked pipe, what I currently have for Stonehaven is approaching 11 years of age. It has been sealed in a glass jar for awhile and I remove enough to be able to pack the pipe once it has been out on my mat for about 1 hour, I then pack the pipe and any left over is set aside and gets mixed with whatever I end up smoking next.
I char light the pipe, tamp it down and relight if necessary. I then smoke the pipe tamping as needed. Since I hardly ever finish a pipe in one outing I then set it aside until I wish to smoke it again then once I've finished I let it cool then carefully remove anything in the bowl with my Laguiole pipe knife being careful not to scrape the inside of the bowl.
I let new pipes, unless they are Meerschaum, Corn Cob or Morta, that I begin the breaking in process on rest a minimum of 5 days before I revisit them with Stonehaven and repeat this process until the inside of the bowl has a protective layer, generally this is light ash but it's a good start toward having a cake form. If for any reason the pipe begins to feel heated to the touch I set it down and allow it to cool. Except for corn cobs I've had 3 pipes burnout in over 40 years, regards.
banjo