I was recently in a session with one of our local Google Partners when this topic was approached. In the four recognized stages of online sales funnels, it's easy to assume buying prospects are in need of nurturing for a projected period of time before making a buying decision.
The reality is all buying prospects enter your online sales funnel at different places. Not all marketing leads are created equal, meaning each buying prospect is at a different interest level than the next.
For example, if your brand sells custom leather courier bags, the reality is that someone actively looking for a leather courier bag would fit more in the Conversion stage of the sales funnel. In that same vein, someone browsing for a new bag to carry their laptop might not want a leather courier bag. They are still in the marketable demographic for a leather courier bag because it meets their consumer needs. However, they will need to be convinced more of the benefits, value, and investment of buying a leather courier bag instead of just a backpack at Target or some other place.
The purpose of content marketing is to create a wide scope of attractive content to best appeal to any buying prospect, no matter their interest level. This is why I'm opposed to withholding buying decision CTAs until after a certain progression of content (ex: no CTA buying option until after email #3 in the email marketing drip sequence).
Your content needs to give any buying prospect to opportunity to convert sooner than they might like, even if they still choose to convert further along in the lead nurture sequence. This doesn't mean you're pushy or sales-y in your CTA, but make it politely obvious that if any prospect is interested, this is the step you would like them to take.
A marketing lead may enter your sales funnel after six months of evaluating your content. The next marketing lead may have just engaged with your marketing content for the first time. One of the greatest advantages for any marketing strategy is being able to prioritize each marketing lead from the beginning. By clearly designating the prospective interest of each marketing lead, you can best nurture each marketing lead with the information they need in their exact moment.