If you drag and drop or paste block of text into TiddlyWiki, it will give you the option to create a new tiddler containing that text, with the title “Untitled” and no other fields.
Is there any way to specify custom fields that should be added, for example a created time stamp?
If you “edit” and then “save” the tiddler, the created and modified fields are added.
Just import the tiddler and it will be named “Untitled N”
Also see this attached tiddler which provides a viewTemplate on [prefix[Untitled]] tiddlers allowing you to rename them. Minimally tested and not refined.
untitled-view-template.json (1.1 KB)
You could customise this as you wish to do much. I will do so myself later. Yopu may want to allow the type field to me changed, eg from text/plain to text/vnd.tiddlywiki
Also a custom drop zone can be created to respond differently to pasting of text, but given your mentioning the created field I think your request was not asking for something so sophisticated.
Did you forget to add a link or some details perhaps? 
Hi Saq, yes I forgot to give the links!
@Sii
Please take a look at https://groups.google.com/g/tiddlywiki/c/37B5uhgbJwE/m/1rU9YBN6AwAJ
Read carefully the post! The code has been developed by @saqimtiaz! and it work great for importing bookmarks! See how it works
Also see https://groups.google.com/g/tiddlywiki/c/YLMOAuLEA3w/m/OGmi0INZBwAJ
An example of something I want to make is the ability to drop on a tiddlers view. Existing tiddler titles added to a list field, protocol tiddlers such as http/https get added to link-n fields. mailto to email-n fields and Plain Text appended to the text field.