Once you have the drawing set up to your satisfaction, Save it as a TCT file to the Template folder. In the "Save As" dialog, click on the down-arrow next to History and select Template. This will save you from browsing to find that folder. Once you're done saving, you can use File/Open and change it back to History or another setting, then Cancel. The change will be retained, even though you canceled.
Now go to the Options/General page, "New Document" section.
change "New document from" to Template.
change "Default templateâ€¦" to your new template.
uncheck the "Promptâ€¦" box if you want to always start with the new template.
Designer, Deluxe, (Professional, Expert, Basic), Platinum
Windows 10 Pro (1803), 64-bit