What do 'timing' and 'a timing meltdown' mean in this sentence?

Question

I have some trouble in getting the exact meaning of 'a timing meltdown' in this sentence.

Here it is:

The doorbell rang, and Mum flapped her hands. ‘There he is. Lou, why don’t you start serving?’

Patrick was still flushed from his exertions at the track. ‘Happy birthday, babe,’ he said, stooping to kiss me. He smelt of aftershave and deodorant and warm, recently showered skin.

‘Best go straight through.’ I nodded towards the living room. ‘Mum’s having a timing meltdown.’

‘Oh.’ He glanced down at his watch. ‘Sorry. Must have lost track of time.’

‘Not your time, though, eh?’ ‘What?’

‘Nothing.’

Me Before You by Jojo Moyes

The context is : It's 'my' birthday party, and a very special guest, my employer, is here today; the cooking is just ready, perfect timing according to my mum, but we are all waiting for my boyfriend who is late for my party.

I could get that 'a timing meltdowns' IS a figurative speech; my guess is that mum is "at some edge of breaking down" or "she is going to be mad" ?? If not please do help me. I am not sure which of the following explanation fits 'timing' in this scenario. (I feel it like, 'timing' here is like 'counting down'??)

In the dictionary 'timing' means:

1. the skill of doing something at exactly the right time
2. the time when someone does something or when something happens, especially when you are considering how suitable this is
3. the way in which electricity is sent to the spark plugs in a car engine

Could anyone help please?

Answer 1

A meltdown is a tantrum, a fit, etc.

The second definition you listed for timing is appropriate:

the time when someone does something or when something happens

The mother is upset that people or actions are not aligning with her intended schedule.