You seem to slightly misunderstand how GDPR works. Tracking in and of itself is not the problem, it's personal data and personally identifying data that is. You can count how many hits your server receives no problem, this is roughly the same idea.
I assume it will be treated as such, too. If you can use a cookie to do this without consent, this is fine too. If you can't then it's not. The same happens for local/session storage: it's cookie-equivalent.
By that measure, any users behind a unique single IP (no IP pooling, no CGNAT, etc) will always be uniquely identifiable. And for IP there's much fewer steps to personally identify the user. The server necessarily sees the user IP.
The best is to not store them before you get consent. Having a temporary access log with a few IPs is probably fine. But keeping all your access logs forever for analytics purposes is not fine anymore.
> Natural persons may be associated with online identifiers provided by their devices, applications, tools and protocols, such as internet protocol addresses, cookie identifiers or other identifiers such as radio frequency identification tags. This may leave traces which, in particular when combined with unique identifiers and other information received by the servers, may be used to create profiles of the natural persons and identify them.
Member States shall ensure that the storing of information, or the gaining of access to information already stored, in the terminal equipment of a subscriber or user is only allowed on condition that the subscriber or user concerned has given his or her consent, having been provided with clear and comprehensive information, in accordance with Directive 95/46/EC, inter alia, about the purposes of the processing. This shall not prevent any technical storage or access for the sole purpose of carrying out the transmission of a communication over an electronic communications network, or as strictly necessary in order for the provider of an information society service explicitly requested by the subscriber or user to provide the service.
In short, this method may fall under the EU “cookie law” above. The use of timestamps may require consent if they are used to distinguish users (even if only for counting purposes). The timestamps may then also be personal data under the GDPR.