The ability of an Open Source Software (OSS) project to attract, onboard, and retain any newcomer is vital to its livelihood. Although, evidence suggests an upsurge in novice developers joining social coding platforms (such as GitHub), the extent to which their activities result in a OSS contribution is unknown. Henceforth, we execute the protocols of a registered report to study activities of a "Newcomer OSS-Candidate", who is a novice developer that is new to that social coding platform, and has the intention to later onboard an OSS project. Using GitHub as a case platform, we analyze 171 identified Newcomer OSS-Candidates to characterize their contribution activities. Results show that Newcomer OSS-Candidates are likely to target software based repositories (i.e., 66%), and their first contributions are mainly associated with development (commits) and maintenance (PRs). Newcomer OSS-Candidates are less likely to practice social coding, but eventually end up onboarding (i.e., 30% quantitative, 70% follow-up survey) an OSS project. Furthermore, they cite finding a way to start as the most challenging barrier to contribute. Our work reveals insights on how newcomers to social coding platforms are potential sources of OSS contributions.