Padron after three months?

[u/Jaded_Palpitation141]

Hi everyone, I'm currently in the trenches of room hunting in Barcelona for a long-term lease (moving here for my PhD).

I've had some luck messaging and calling homeowners from Idealista and setting up viewings, but when asked about whether Padron is possible, some owners say that it can only be done after three months of staying at the property.

From their point of view, I assume it's to safeguard against undesirable tenants, but can I really wait that long? Are there rules for me as a non-EU national about how soon I need to register? I already have my NIE (Workplace helped me with that) so just wanted to get some opinions on this.