We stock and sell a range of ready mixed specialized cements to secure your posts firmly in the ground. Two products are:
Posthole cement -
a ready to use mix especially formulated      for posthole strength. (see brochure) Rapid Set -
This mixture you add to water in the hole, do not      stir or mix and sets in 15 minutes. (see brochure)     
You can start to install the sheets, because the post is set.