How to manage time between product and marketing?

Curious to know if you set aside a few hours a day marketing, one day of the week or just do it when you're close to launch.

I guess that consistency is key here, so it's probably a good idea to idea to do it periodically.

Which approach has given you the best results?

I'm currently working on a marketing side project that is taking much more time than expected, so I'm not very sure if this is a sustainable approach.

Thanks!