Weigh In?

there aren't really rules or anything...

As often as you feel comfortable with (daily, every other day, weekly, monthly, etc.). What matters more is that you do it in a consistent setting: same time of day (usually right after waking up and using the bathroom but before eating/drinking anything) and wearing the same amount of clothing.

I weigh daily. But keep in mind if you do it daily expect fluctuations and don't emotionally react to them, the scales going to jump around a bit. I record once a week though based on the average after tossing anomoly's.

It's an entirely personal preference with pros & cons to all options.

Weighing Daily - can be helpful to establish more data points to get a more accurate trend and can help some people to better understand their body's normal weight fluctuations, but can be demotivating for other people if they can't emotionally disconnect from the scale and can't rationally evaluate the data.

Weighing Weekly - good for those who might become unhealthily obsessed with the number on the scale and might be emotionally attached to seeing the numbers fluctuate up/down daily. Should give a relatively decent trend over time if consistently done under the same conditions. However, if you have a gain, and you're not logging accurately you aren't going to know if it's fat or water retention because you have less data.

Some people do weigh less frequently, particularly if they have had strong emotional reactions, again this can be beneficial but you also have less data available.

Other ways to measure progress can be used alongside the scale, the scale is just one tool of many. Progress pictures, measurements, clothes fit and other non-scale improvements such as fitness & health can also be useful.