When to fill the grow bags with compost?

Maybe a silly question, but is there any advantage in buying the compost (shop bought) early and filling the bags in position ready for when it's time to plant the veg and potatoes? Or should I just wait until I'm ready to plant. Does it need time to settle or is keeping it in the bag better as it's less likely to be affected by a late frost?

Just thinking generally and wondered if anyone had an opinion either way.

Thanks

If you get across to Wyevale (Rowena), they have an offer of 3 bags of multi-purpose for £10 instead of £4.99 each.

But living closer than I do - you probably knew that!

That's 3 1/3 bags! Shame about the 1/3!

I use a Seed Compost for sowing seeds in trays (big seeds, like beans, don't get the Special Treatment!) - I think it works better than multi purpose.

When I planting Potatoes in containers I put 4" of manure in the bottom, then plant the potatoes into about 4" of compost. So I reckon it will be easier to put the spuds in and then pour in more compost on top (rather than "planting" the spuds into a pot full of compost).  I then pour in more compost as they grow ("Earthing up") until the container is full.

I would suggest you keep the compost in the warm (i.e. not in a cold outdoor shed) otherwise it will be very cold when you plant - so if you put into containers now, and put in a cold greenhouse, it would be cold when you plant.