Got my first tubeless bike three weeks ago, no punctures yet, so I'm definitely a tubeless newbie also.
My tires have Stan's sealant in them. Their instructions say more sealant should be added every 2-6 months, so if you haven't done this for a while you should probably try it first.
Any real world suggestions on how frequently to add sealant and how often? 2-6 months is a pretty wide range.