In the western Ukr heartland this was likely before 1800. But in the case of Malorussia in the center, including Kiev, there was no such self-labelling in
1897 when they reported themselves as Malorussians in the census.
Ukria is a Bolshevik construct resting on the precursor construct of the Austro-Hungarian Empire, which itself rests on the assimilation policies of the
Grand Duchy of Poland and Lithuania which annexed the western lands of Soviet delineated Ukraine centuries ago. The western Ukrian dialect
was foisted on the population of Soviet Ukraine as if it was the self-evident one. It should have been "surzhyk" which sounds more like Russian.
This linguistic reality persisted until the break up of the USSR.
The Bolsheviks also stapled on the ethnic Russian lands of Novorossiya, spanning from Odessa to the eastern side of the Dnepr Riiver, to their
concocted republic using the excuse that Ukraine needed industrial capacity. None of the local population was asked if they wanted to join Ukraine
and they certainly did not speak Ukrainian and consider themselves Ukrainian.
The key detail is that Ukraine was mostly depopulated after the Tatar-Mongol horde occupation which involved the razing of Kiev to the ground. So
there was a settlement process afterwards and all the major cities in the south and east were founded by Russians. They were not conquered and
there was no Russian "occupation" of this land.
There was no such thing as Ukraine in 1200. Kievn Rus was not any Ukraine and there was no such thing as a Kievan State. A fabrication of
modern day western revisionists who are trying to fake up a Ukrainian ethnic state in 1100. Basically parroting what Ukr ethno-fascist revisionists
do. They claim that "Ukraine" adopted Christianity in the 980s and that Knyaz Vladimir was a Ukrainian. That would be a surprise to him and
the rest of the people living there at the time. None of the "beresti" (birch bark records using Slavic runes) refer to anything called Ukraine.
The name Ukraina is just a form of Okraina meaning border region. It points to a derivative ethnicity reflecting the occupationhistory of first the
Tatar-Mongols and then Poland-Lithuania. Western Ukraine is definitely a transition region.