Yes, that's correct. WTP-CW Avios upgrades are regraded by many as something of a "sweet spot" in terms of value, and at the moment there are some very good WTP fares coming back from the East Coast USA.

Note that while people (and BA agents) colloquially refer to the additional costs as taxes, that's not actually true in the sense of being govt imposed. They are wholly BA surcharges, but tbh other than some people finding it irksome/deceptive, the difference is ultimately rather academic in that you still need to pay them! More accurately, you may see people refer to TFC - Taxes, Fees and Charges to cover all the extra costs.

You can see the peak/off peak days on BA.com but you may find it easier to see them all in one go, e.g. here: https://www.headforpoints.com/2019/0...calendar-2020/

Lastly, a belated welcome - didn't spot it was your first post. Note that the system will limit you to only 5 posts in your first 24 hours