Thanks for your question. It is timely.

Garlic bulbs are unlike fruit. The ripeness of the latter can be strongly influenced by numerous external factors. The size of garlic bulbs and when they should be dug up, is largely dependent upon its external foliage. Hopefully you are dealing with hard neck garlic. The other variety – soft neck garlic – does not grow well in Minnesota. See:

https://savvygardening.com/hardneck-vs-softneck-garlic/

One of the best indicators of impending garlic harvest with hard neck garlic is the appearance of garlic scapes. You may or may not have seen these in your past garlic patches. Clip off these scapes and use them in your salads. Great and tasty addition. See:

https://www.thespruceeats.com/what-are-garlic-scapes-and-how-to-use-them-4783219

https://chatelaine.com/food/garlic-scapes-faq/

More directly and with respect to your question, keep watching the above ground leaves. When about half of them turn brown and begin to flop over, your garlic should be dug up. At this time (late-May 2024), it is way too early to harvest garlic. See:

https://www.youtube.com/shorts/X6ZGJ-GyzdU?app=desktop

https://www.groeat.com/post/grow-your-blog-community

https://extension.umn.edu/vegetables/growing-garlic - harvesting-868162

Good luck. Please get back to us if you have any further questions.