While the goal at the last UNFCCC COP 24 (2018 in Katowice, Poland) was to agree on the Paris Rulebook and underlying decisions to make the Paris Agreement fully operational from 2020, decisions in terms of Art 6 have been differed to COP 25 (for further details see here). While countries can plan ahead, additional guidance from the COP would set a clearer path for Parties fully include and develop efforts on blue carbon as part of Art 6.
References
Herr, D., von Unger, M., Laffoley, D., & McGivern, A. (2017). Pathways for implementation of blue carbon initiatives. Aquatic Conservation: Marine and Freshwater Ecosystems, 27, 116-129.
Herr, D., Chagas, T., Krämer, N., Conway, D., Streck, C. (2018). Coastal blue carbon and Article 6. Implications and opportunities. Amsterdam: Climate Focus. Available at: https://climatefocus.com/sites/default/files/20181203_Article%206%20and%20Coastal%20Blue%20Carbon.pdf
UNFCCC. (2015). Adoption of the Paris Agreement Report No. FCCC/CP/2015/L.9/Rev.1. United Nations Framework Commission on Climate Change. Available at: https://unfccc.int/resource/docs/2015/cop21/eng/l09r01.pdf