Write some script - A Timeline Script

We are wanting some script written up that will take an array of dates and post them on a timeline. By default we are looking at the timeline going back 6 months, but having the capacity to change this date would also be required. Effectively, this script will be passed dates in an array and the script will need to calculate how far along the timeline they need to appear and apply a symbol (and title/hover for event type). Each event on the timeline may be different event type (passed in with the array), but duplication will occur so colour coding the event symbol would also be a requirement. This script will be re-used in multiple formats so clean code is a must (our team could build this, but we are outsourcing to save time). I have attached a photo of a design mock-up. Please ask if you have any queries.