When to mow the "meadow"

[Stere]

Have a  20m square of grass I have planted some fritillary bulbs in

 

Whens best to cut it to encourage them to spread?

 

I suppose after they have seeded.....

 

 

From google:

Quote

Fritillaria seed ripens in mid to late summer and is best sown as soon as ripe or soon after in autumn.  While older seed may still be viable it develops germination inhibitors that can make late sowings germinate erratically.

 

So check seeds heads & cut grass has soon as posibble after then go ripe?