Welcome to Aperture, From what you say i would make a folder for the year, sub folders for every month, and a project for every day. This is my exact set up and it keeps the library neat and easy to navigate, as well as being easy to find images without searches. I also keep the same structure on the HD. for the Referenced Images.
It is essential to split that one big import First of all.
To sort them by date: In Browser View go to the little Q at the top right and click. Now click Add New Rule, and click Calender on the drop down list. Click the little circle that has a minus sign in the middle to get rid of all the other search fields, you don't need just now.
Click a Date then select New Album with current images.
You can use command click, or **** click, to select multiples.
This is the important part: It is essential, that you do then split them in to Projects and don't leave them in a single Project. Projects are the the Containers for your Master Images, though they can be viewed in folders, It is only the Project that holds the master. You are best to keep them limited to about one thousand each. Keeping track of the Masters seems to cause a lot of problems for people here on the forum, but not if you Start off correct. To do this, keep the Album you just dropped in to a Project and do all your work from this. In this way you never have any duplicates in the project. You can work with gay abandon in the album and never get in to a mess that is difficult or impossible to reverse.
Allan