I agree with Laurie!
I do not work to a 'hard & fast' regime, although my website suggests different but then it is only "a guide"
I look to what is growing at a given time e.g.
When the crocus start to flower I start my 'sowing programme' and when the annual weeds start emerging I plant out such things as onion/shallot setts.
It is not a very scientific way of doing things but it seems to work for me!