advice needed on my first job

[robwah]

i have got to plaster a celling measuring 4m x 4 1/2m plus down 30cm to picture rail just skimming over old plaster.

how long should this take for two coats plus wet and dry trowling?

and how many bags of multi finish should i need??

 

[dpbeds]

I'd take 3 bags of multi.
I'm not that quick but you should kill it in a shortish day.
That is providing it's just turn up and skim it!