This study uses group-based trajectory modeling to analyze posting behaviors in the Iron March and Fascist Forge forums, known for promoting right-wing extremism and violence. By applying multinomial logistic regression and analysis of variance, the research explores how the timing of entry into these forums influences posting trajectories. The findings reveal both similarities and differences in posting behaviors across these platforms, providing insights that could help law enforcement and intelligence agencies develop better frameworks for identifying online threats. The study concludes with a discussion on the implications, limitations, and future research directions.