To get a free upgrade to the next major Cubase version, you must activate/redeem your new license on or after the official start date of the grace period (usually starting several weeks before a new version is released, around autumn).
How the Cubase Grace Period Works
• The Activation Date Matters: Eligibility for a free update depends strictly on the date you redeem your Download Access Code or activate the license in the Steinberg Activation Manager, not the date you purchased the code.
This part is wrong. You can just delete it from your post for the rest to be helpful.
How it has worked in the past. This is not a guaranteed method.
Just take advantage of the sales (but don’t wait for Black Friday - Steinberg doesn’t have one).
PSA: This info is wrong.