When to cut down cosmos?

Excuse me, could you possibly offer some advice on the matter of cosmos pruning? I've been hearing differing opinions on when is the ideal time to trim back my cosmos plants. Some gardeners swear by pruning in early spring, while others claim that late summer or fall is the key. Could you please clarify this for me? I'm particularly interested in understanding the reasons behind each recommendation, as well as any potential benefits or drawbacks associated with pruning at different times. Additionally, would it be helpful to prune according to the growth stage of the plant? Your insights would be greatly appreciated, as I strive to achieve optimal growth and flowering in my cosmos.