Private Label Rights content is content that is licensed for use by another entity. It can be a useful addition to a website and a great way to provide additional value without creating more content yourself. It can also make up a great part of your longer term content strategy.
When deciding whether you should add PLR content to your site it is also important to remember that you need to focus on providing real additional value to your members. Just because you can do something doesn't mean that you should. Also you should not being adding filler content to simply make your site look like it offers more than it does whilst providing empty content.
Everything that you add inside to your website should be adding value for your members and be in line with the core value offering of your website. As long as you meet these criteria you can add as little or as much PLR content as you want. With that said it is possible to provide so much content upfront that you overwhelm your members, or worse content that provides a contradictory message. For this reason the best time to add PLR content is probably going to be when it fulfils a need for your customers, that you don’t currently provide for and supplements your primary product.