Most people start burning-in at the end of the main exposure.
You could burn-in first - but most people do it after the main exposure
The important thing is to keep the order the same.
As for dodging - it depends how much dodging you have to do.
My timer bleeps at me to help me keep the time - and I like to listen to the bleeps to help get the timing right before I start
If I only have one bit of dodging to do it at the end of the exposure - watch the timer counting down, jump in at the appropriate point and then dodge until the timer runs out - that way I don't over-dodge by keeping going for a little too long - as I sometimes loose count of the time while I am doing it - or enthusiasm gets the better of me.
It doesn't matter when you dodge - just how much
Some people break their main exposure up to fit to the times of the dodging sequence – but I don’t like to do it – as with my enlarger 3off 4 sec exposures are not the same as 1 off 12 sec exposure – due to bulb warm-up and anti-surge effects in the transformer.
What is important is to give yourself plenty of time to dodge, so most people aim to have a base exposure of more than 10sec.
Trying to dodge for 10% of a 10sec base exposure requires skill and dexterity
Trying the same dodge procedure if the base time is 30s is considerably easier
I practice the dodging and burning sequence without paper in the easel until I have the sequence sorted in my own mind – it can take quite a few dry runs to get right