Planting raspberries - preparing plot with manure - why wait before planting canes?

Hi,

Am currently in process of digging over newly acquired allotment plot ready for growing raspberries, blackcurrants and gooseberries.

Of course this digging and weeding is taking some time to do it properly, and my 4 year old daughter/assistant head gardener is growing rather impatient...and the nagging is starting...."when are we actually going to do some proper things and plant something Daddy." Anyway have nearly finished preparing plot now, apart from adding some horse manure to enrich the soil, which i plan to do in the next day or so.

I read the growing guide for raspberries on this site and with regards to digging and incorporating organic material it said, " Ideally soil preparation should be complete a month before planting; at the very least you should allow two weeks to give the earth time to settle."

Sorry if I am being a bit dim but what does this refer to - is it saying that there would be too much air in the ground as recently dug and therefore canes wouldnt be properly anchored in the soil? Or is it a reference to the manure/organic matter being too harsh/strong for the roots and that this needs to settle down? Sorry, am a bit new to this - hence "germinator" label

Maybe I should rephrase my question - if i give into pester power and plant the canes this weekend into ground manured a few days beforehand, will we regret it?!

Thanks