Number 10. When it’s on sale
Number 9. Days that end in “y”
Number 8. When the blade gets dull
Number 7. Right after the neghbor gets a new power tool
Number 6. Right after I figure out how to use the last one I bought
Number 5. When the lumber pile starts taking up car space
Number 4. When the old one breaks
Number 3. When my brother in law comes to get his tool back
Number 2. When the last one I bought is paid off

And the Number 1 best time to buy a power tool:
When my wife’s not looking