Thank you for your question!

 If you planted asparagus from the seed, you should generally wait 3 years before the first harvest. If you start from 1-year-old crowns (the recommended manner), harvest can begin to a limited degree the next year. Harvesting early will drastically reduce yield as well as quality of home-grown asparagus.

In addition, the asparagus plant is made up of top (ferns), crown (buds) and roots. All three are vital to a productive plant. The ferns are the “factory,” which, through the process of photosynthesis, produces food stored in the crown and roots below ground. The number of vigorous spears in the spring depends upon the amount of food produced and stored in the crown during the preceding summer and fall. Producing a good crop of ferns is necessary to ensure a good crop of spears the next spring.

Do not cut back the old ferns at the end of the season until they are completely dead. In the fall, nutrients move from the dying ferns to the crown. Removing the ferns too early weakens the crown and may thereby reduce the size and number of spears the following spring.

Here is the article where I pulled some great information from: 

https://extension.unh.edu/resource/growing-vegetables-asparagus-fact-sheet

In addition here are some of the most common questions about Asparagus:

https://aggie-hort.tamu.edu/archives/parsons/vegetables/asparagu.html