I created a spreadsheet to tell me how long a stack of new buildings would take to get built. It's not perfect; it doesn't take into account the possibility that the construction time might take longer than the time to acquire the appropriate resources, and it doesn't take into account the production multipliers that some buildings give. But it's not awful.

I did it in OpenOffice, so if you actually need to use Excel for some reason, you might try the ODF plugin for it. (And let me know if that works.)

It's attached.

Oh, the red boxes are for data you need to fill in manually. Green boxes are output. Blue boxes are, well, blue.