VIP when used on farms in the right way is absolutely awesome. There are 2 uses for VIP on farms.
The first use is to gain an extra march for gathering VIP level 7 grants this extra march. Save almost all VIP activations you receive until this moment in time. The extra march and the fully built fields receiving the resource boost makes for an impressive difference in resource collected.
Not that the 1 hour of VIP is sufficient to activate your gathering armies and also hit the harvest skill.
Harvest skill gains are increased whilst VIP is active.
Before vip 7 you will want to build fields. My own personal method for building fields with vip is this.
I only use the VIP if I will be able to be active to utilise it, this for me is weekends. On a Saturday I will activate VIP and golden hammer on a farm and I will spam the fields continuously. This using the free time saved to it maximum potential and I think I used the free 5 min speed ups with vip to get all resource fields to lvl 9 or 10 within a few minutes of deciding to increase them.
Monday – Friday I do not use golden hammer on farms and I do not use VIP