If you want to have the smoothest experience when the new Patreon perk version of Sprucemarks launches, most likely on January 1, 2020, you can absolutely become a Patreon ahead of time.
Once the new perk version of Sprucemarks goes live, you'll connect to your Patreon account via a login button. Then Patreon will ask if you want to allow Sprucemarks to check your info / contributions.
If you are either an active contributor (any monthly amount) OR if you've donated $7 or more one time OR over time, Sprucemarks unlocks.
You absolutely DO NOT have to donate every month for the rest of time. $1 a month gets you access that month and anytime your lifetime contributions hit $7 you are set ongoing, no monthly donation needed.
Your support means so much me so a huge thanks to current and future Patreons. You inspire me to make things even better in 2020 and beyond. ^_^
P.S. - The current version of Sprucemarks is free all this month and it can be installed from https://chrome.google.com/webstore/detail/sprucemarks/fakeocdnmmmnokabaiflppclocckihoj?hl=en