How long to leave manure on the soil before planting

I've prepared my new herbaceous borders and have all my plants potted up (very thankful it was a mild winter!).  To give everything a good start, I want to lay manure on top of the soil and let the worms do their work but I also want to get the plants in as early as possible.

Any tips for how long I need to leave it before planting?

I didnt use manure on mine this year, instead I used soil conditioner, so I cant really advise, I am experimenting and it is the first time I have used it.  Good luck with your borders.

Three months at least for fresh manure.  I get fresh manure delivered in the spring and spread it in the autumn and the autumn delivery is spread in March.

I'm hopeful of getting some well rotted stuff - over a year old - so the acidity shouldn't be a problem. 

Stephaniejane - what soil conditioner did you use?