Is there a best time to submit a job application?

[Remind]

The vacancy was advertised yesterday and I've done the application etc.

Closing date is 10 March. Is it too early to send it in now, looking like you had it all ready and are applying for loads of jobs, or is leaving it the last minute worse?

Or does it matter at all?

Also, it's a demanding, fairly senior job with quite a defined skill set. Does the short closing date suggest they've already got someone lined up?

There will be huge variation in recruiters. Some may not look at any till the closing date.
Me, I look at applications as they come in. If some one truly fabulous applies I will invite them to interview ASAP in case they get offered something else and I miss out on them,
The rest I will rate as Yes, Maybes and Nos. Then after the closing date I will invite the yeses to interview.

I always wait till the closing date to look at all the forms so wouldn't matter to me but given some might look as soon as it gets there if you have finished it you might as well submit it.

I wouldn't wait until closing date, if only for the fact that a friend asked me to be a referee for her for a particular job with closing date this Friday and she called last night to say job advert was removed and replaced with a note saying due to huge response no more applications are being taken. She had not filed her application and wasn't planning on doing so until today, not sure what her reasons were but it matters not now.