If I say I want this job to be done in 5 days, does this sentence have connotation of completing it in the next 5 days. However, what I'd like to express is a expected processing time for this job, I don't want to start the job from now. If this sentence is not suitable for what it should mean, what should I say?
So basically, you're comparing
I want the job to be done in 5 days.
I want the job to be done within 5 days.
As per your request, that you don't want to start the job right now, the more appropriate sentence would be the latter. However, the first one too doesn't restrict you that you HAVE to start the job right now