If you were working for an employer who sponsors you for PNP, it depends on what province you are in what are the rules of the PNP. I do believe you have to be on a regular work permit but maybe it works for a working holiday too. The problem would be, if you could apply while you are still on working holiday and then have a problem getting your work permit changed to a normal work permit and your PR is not done when your working holiday visa expires, what would happen to your application. You can look at the PNP's in different provinces but especially after you are in Canada and have found a job, look at the PNP in the province you are working in and ask them about all details.
If it's a skilled job, there is in most cases no time limit you have to have been working for the employer before you apply but many employers will not apply for you until you do at least your probation period, normally 3 months or even after 6. Processing time also varies, maybe from 6 months to a year to get PR.
Anyway, find the employer first, try to get your work permit changed to a normal skilled permit, if that doesn't work, try to get an AEO and use that to apply under PNP or FSW. To get a normal work permit, you need an LMO which is harder to get than an AEO. That is unless you fall under the categories of people who don't need an LMO for a work permit, then it might be really easy, see
http://www.cic.gc.ca/english/work/special-tech.asp