ISIS existed from 2005, it's a direct successor to Zarqawi's Al Qaeda in Iraq. Which was a separate entity which joined Al Qaeda as a franchisee so probably 2005 is the fairest time for its establishment. It became the Islamic State in Iraq, then ISIS, then formally 'Dawlah' IS as a 'Caliphate' once they reinvaded Iraq from Syria and took Mosul.
Now, the rest is more interesting. ISI under Baghdadi sent support to the Syrian rebels- Jabhat al Nusra, the 'Support Front', now Hayat Tahrir al Sham and supposedly independent of Al Qaeda (now officially Hurras ad Din, in Syria)- while it was still under the umbrella of Al Qaeda, its very name tells you that it did exist before the US gave them weapons, though it was not significant at the start. They had a lot of success though since they were ruthless, got support from US allies and eventually grew. In 2013/4 JaN split along the lines of Al Qaeda and ISIS loyalties, and a bunch of other groups joined ISIS, they reinvaded Iraq and took Mosul etc then became enemy #1.
In terms of support for ISIS/ JaN from the US, there was quite a lot of it though most of it was clandestine and indirect, and hence deniable. By the measure of the US itself they definitely supported ISIS- almost all the top ISIS leaders including Baghdadi were held and released by the US previously, they operated with impunity for years and were armed and trained via operations like Timber Sycamore. Ironically, these are exactly the accusations the US levels at Iran to show they support Al Qaeda... To be fair, most of the arming and training done was to 'moderate rebels' that somehow despite the no doubt careful vetting joined decidedly non moderate ISIS later, and not directly to JaN, though they certainly knew that US allies (Turkey, Qatar) were supporting JaN directly. That is also the source of the infamous 'McCain meets Baghdadi' photo, while it isn't Baghdadi the 'moderate rebels' he was photographed with went on to become senior ISIS leaders. The US never, bar one occasion, significantly bombed IS if they were attacking the 'correct' targets and infamously never targeted their main source of revenue, oil, since most of that money was going to/ from Erdogan's son. The one occasion in which they did attack ISIS on a frontline with Assad they 'accidentally' attacked Assad's troops instead, and handed ISIS the main defensive position overlooking Deir Ez Zor airport. Indeed, that attack persisted so long that the Russians allegedly only stopped it by directly threatening to shoot down the Danish and Australian planes involved, after the senior US officer on the deescalation line was for some reason absent for 45 minutes.
Overall there's no doubt in the slightest that the US under Obama was at minimum fine with ISIS, so long as it was attacking Shia militia and Assad, supported those who later joined it as 'moderate rebels' and even post Caliphate declaration tolerated it, so long as it was threatening their mutual enemies. It was only when they started threatening US interests that they became an evil that had to be stopped. It's very doubtful that Obama had any direct operational knowledge of most of this, but then if you use that excuse for him you have to use that excuse for Bush as well.