Ask HN: How to set better deadlines for side projects?

Hi HN,

I'm working on a lot of side projects but when estimating time and setting a deadline for side projects I often miss them despite being on time with regular work.

I noticed that my side project work often involves a lot more learning and using skills that I don't already have so it becomes difficult for me to plan ahead and be able to estimate how long creating something using a new skill will take me (for example creating something using a library that I need to learn). This isn't necessarily an issue except when I keep missing my own self imposed deadline a project that I only wanted to spend a month on blows up to a year as I keep going down a rabbit hole to learn new things.

How can I better set deadlines and goals in side projects?