Rendering takes a little bit longer than plastering and the weather conditions play a roll as well. Expect it to take between 2 to 3 weeks to render a 4 bedroom detached property. This will also depend on what type of finish you are after and if they are using a 1 or 2 coat system of application. Traditional lime rendering on older buildings is a more specialist job and may cost more depending on your plasterer.
If you are applying render for the first time on your house you need to make sure that you are adding value to the property and it fits well with the surrounding properties. Render is usually applied to brick work that is deemed unsightly and also offers a protection against the elements that some brickwork requires. Also it is best to inform your building insurance company that you are about to render the house, and they will be able to advise you accordingly.
You will need to additionally hire scaffolding. Depending on where you live in the UK costs start from around £400 a week.