Sweetcorn Cobs Starting to Set

I had a great surprise yesterday to discover that the first of the sweetcorn cobs have appeared. It is my first year growing sweetcorn so not sure what to expect. I was expect these to be about 2m tall before the cobs would form but these are less than 700mm tall.

These plants were sown back in March in a propagator. I had a low germination rate in the earlier sowings so I have ended up with about a dozen plants all at different stages of development and size.