The initial version of the Secret Managers for Bamboo plugin took 3 weeks to build, including learning the Atlassian SDK, Bamboo API's and brushing up on my Java skills, as this is the first time I wrote an add-in for an Atlassian product.
The MVP demonstrates the core functionality: connect to an external secret manager and have secrets ad-hoc resolved during a build. I chose to support only Azure Key Vault and HashiCorp vault, because these were the secret managers I knew about at that point.
I started working on the MVP in the 2nd week of January, and had set the deadline at January 31 for submission to the Marketplace for review (to prevent myself from initially building too much). As part of this submission, I also had to prepare screenshots, marketing texts and a documentation website (available at https://windtunnel.io/products/smb). The review itself took over 10 working days but luckily did not result in any remarks 🥳, so the plugin was eventually released mid-February at https://marketplace.atlassian.com/apps/1221965/secret-managers-for-bamboo?hosting=server&tab=overview.