In 2006, the United States government gave $23.53 billion in overseas development assistance. When did these programs start?
Once again Wikipedia to the rescue
For the first hundred years of the United States' existence as a country, government aid was practically nonexistent. It was generally considered that the Constitution did not authorize the government to use the people's money for foreign charity.
The quote goes on to discuss US foreign aid from WWI onward. Certainly US foreign aid accelerated dramatically in tandem with US involvement in/engagement with the rest of the world during the World Wars.
However, the situation is not so simple as that would make it sound.
- Much of US foreign aid has always been non-governmental, administered by private foundations and charities. Although the USG has been historically isolationist, the US public has always been very charitable, probably because the US lacks a state church.
- Some discussions of foreign aid lump together cash payments with the right to buy US products, but most people see a difference between a cash payment and "You have the right to buy US wheat at a discount". That is particularly true for development assistance, and frequently it isn't clear whether the intent is to benefit the foreign country or domestic farm production.
If you want a more detailed answer, you could use OMB's summary of Federal outlays by year, which doesn't seem to list much before 1940.