Technically you cannot pre-add an electronic Signature only Signature block or field. You could set the workflow of the Template to send it to you first as Recipient 1 then when you get the email notification you could actually sign the document before it went to them as Recipient 2. That would be my suggested route....of course there is option B

Option B, send an envelope to yourself with a blank document and with just a Signature tag that you would sign. Then upon completion take that PDF document and add it to a Template. The Template now has a document with your electronic signature each time you send it under a new envelope. I do not recommend this but it is an option, I believe all signatures should be done at the time of the envelope sending process or workflow as then you have History and Security around the process. Lets say you accidentally shared your Template with your preset Signature, Now that Template could be used without your knowledge with your preset Signature.

Thank David very helpfull!

Have a great day!