One of the more difficult parts is knowing when these public events and how often. Luckily one website has you covered. Destiny Public Events is dedicated into showing approximately when an event will occur on each given planet. The coolest part is that it will even tell you what area of the map it will occur and also what sort of event will be occurring. They do indicate that this is based off of potential but after trying it for myself I would say it’s a very useful tool that might be off maybe seconds to a minute max.
With the Queen’s Bounties and other Bounties occasionally needing events to be taken care of to be cleared, this is an extremely useful tool for then. It also helps hunting a bit easier if you are just looking for a change of pace rather than the same old maps with the same enemy spawns every time.