We had a commercial chipper in to chip a large ash tree which had fallen down. How long until the chips can be used on the garden? A year? Two years? !! I have a huge pile.
The chips tend to take up some nutrients such as nitrogen, but this is not much and it is released again. Fears about spreading fungus disease are unfounded.
But too much mulch on heavy soils can cause poor growth by keeping the soil too wet.