Skipping time is one of the most dangerous things you can do as a writer. While it can be necessary, it very rarely is, and when it isn't, it can be one of the worst ways of betraying your audience.
Probably the worst one I've ever seen was in the beginning of the book "The Grace of Kings" by Ken Liu. In the first chapter, he introduced to me a protagonist that I honestly really, really liked and wanted to see him do great things and overthrow the oppressive government. But guess what he did to me in the beginning of the second chapter? Surprise! It's seven years later and he's a completely different person now! Even worse, nothing in that first chapter ended up having any relevance to future events whatsoever. I would never see that fun, interesting character again. I had never felt more betrayed by a writer, and I will never read another book by Ken Liu. I would have dropped the book right there if I hadn't still liked the new Kuni.
An example of a good time skip was in Attack on Titan (the anime, not the manga). After the first two episodes, where I was introduced to a protagonist I really liked, that I both sympathized with and admired, the main characters had to go through five years of training, and that obviously wouldn't make a very interesting show, so they mostly skipped it. There are two reasons this was okay: first, they actually did include two episodes that zoomed in on the training, which made me feel that I hadn't missed out on anything major, and second, no significant character development took place that I didn't get to see.
So yeah. Those are the two requirements you have to meet at least one of whenever you do a time skip: either don't significantly change the characters over the skipped time, or show me some excerpts from it. If it's a long time you should probably do both.