Going through Lamport's video lectures (https://lamport.azurewebsites.net/video/videos.html) is a great way to get the basics down. It proceeds at a fairly lesiurely pace so if you just block off some amount of time every day (say a video or two a day which usually works out to 30min - 1 hour depending on how well you want to practice the concepts in the video) you'll be able to use TLA+ by the end of a week or so.
It's so low-level, every time I try to look into it I am reminded of the 6th normal form, it's such a mess to gather all the parts of the condition into one big conjunction...