Timeline and Tracking Gantt are two separate views. You can print only one view at a time. I suggest select the Timeline and use Copy Timeline button in Format to copy for presentation, and then paste this image in paint brush application. Then, select Gantt Chart and use Copy Picture option in Task ribbon and then paste this image below the previous image. Print the final image to the printer
Alternatively you should be able to take a screenshot of the timeline and use that image in the header (or footer) of the printout. Unfortunately that would have to be done manually every time you would like to print. However if your printout is more than one page it will show again on all subsequent pages.