SUBSCRIPTON OVERLAP V4 & V5

I bought 360, version 5, on a CD.  My current subscripton (version 4) has 3 weeks remaining.  If I install version 5 now, will the subscription date be effective immediately, or when version 4 expires?

 

Are there any special steps I should follow to install version 5, or can I simply load the CD and follow the prompts to update from version 4?  Norton Utilities is also on my machine.