As soon as you publish your site with content, you may start creating some Web 2.0s to point them initially. And throw some social signals to it gradually. For every new page you create repeat the same steps initially. If your site is constantly being updated for 2-3 months with additional indexed pages equipped with Web 2.0s, you can start pointing PBNs to it. Make sure you analyze the following factors of the competitive sites ranking on top SERPs:
i) How many index pages do they have in what span of time?
ii) How many unique domains they have got links from?
iii) For how long they have been getting their backlinks? (Check the link velocity)
You may need to copy or improve your steps for your website accordingly.