Show Posts By Upcoming Date…

I have a site that i am working on that shows events for children in their local area.

Each post has a date when the event takes place and the date it finishes. I was wondering if it would be possible to order the posts by that upcoming date? so for example, the post with the earliest start date would be at the top of the page. I have had a look at custom fields, but i am not 100% how it could be done.

I have had a look around for a plugin that can do the function, but i can only find plugins that show posts that you put a time stamp on.

Can anyone help?

Thanks