Set up bleed when you create your document.
If you know in advance that your artwork will print to the edge of the page, you can set up bleed when you create your document, using a value specified by your printer typically.125 inches.
Choose File > New Document or Choose File > Document Setup depending if this is a new document or adding bleeds to an existing document.
Click Bleed and Slug to expand it. Enter the bleed in one of the fields, and click the Make all settings the same icon to extend the bleed evenly on all sides.
Create a PDF file that includes the bleeds.
- When it’s time to handoff the document for printing, save it as a PDF file to ensure that bleeds are saved correctly.
- Choose File > Export. Select Format:Adobe PDF (Print).
- In the Marks and Bleeds section, select Crop Marks in the Marks area, and Use Document Bleed Settings in the Bleed and Slug area.
- Click Export to save a PDF file with correct bleed values that is ready for handoff.
Reference Link:
https://helpx.adobe.com/indesign/how-to/set-print-bleed.html