The TIMER survey with MUSE has collected high signal-to-noise and spatial resolution data of 21 nearby barred galaxies. The main goal of the survey is to establish the cosmic epoch of bar formation, which in turn indicates the time when the main disc in disc galaxies settles dynamically. This dataset allowed studies of the stellar kinematics and population properties in the inner kpc with unprecedented spatial resolution. In this talk, I will present a summary of our main discoveries, including: 1. A wide range of bar formation epochs at fixed stellar mass, which is challenging to interpret in the context of the downsizing scenario, whereby discs settle first in the more massive galaxies. I will show that these results are consistent with JWST studies on the cosmic evolution of the bar fraction. 2. Establishing the presence of bar-built nuclear discs with kinematics and stellar population properties that contrast those of central merger-built spheroids (aka classical bulges). These nuclear discs are shown to be the exponential (pseudo) bulges in photometric decompositions, and to form inside-out over long timescales. This provides a new paradigm to understand the central region of disc galaxies. 3. Combining ALMA and MUSE to show the impact of stellar feedback on cold gas within a few hundred parsecs from the centre. I will also discuss the challenges we faced in the context of full spectral fitting to derive stellar kinematics and population properties.