"Conversational" means different things to different people. Ordering food is not the same as discussing politics. Let's break down realistic timelines by goal.
Basic Survival (1–3 months)
With 15+ hours per week, you can handle restaurants, taxis, and simple shopping within 1–3 months. You'll sound like a toddler, but you'll survive.
Functional Conversation (6–12 months)
At HSK 3–4 level, you can discuss daily life, explain problems, and make friends. You'll still struggle with abstract topics and fast speech.
Professional Fluency (2–3 years)
HSK 5–6 plus real-world practice gets you to professional working proficiency. You can negotiate, present, and navigate bureaucracy. Most learners never reach this level because they stop before year two.