E30 Zone

I am doing a cam belt change on an early 323i M20. I want to take the cam pulley off so that I can replace the leaking cam seal. Do I set the cam pulley and crank pulley at TDC and loosen the cam pulley before removing the belt? I could then remove the loosened cam pulley once the belt is off. Or do I set the two pulleys to TDC, remove the belt and then loosen the cam pulley?
This is the early M20 with the dizzy on the top of the motor.
Any guidance would be appreciated.
Ta
Xavier

when i changed the smaller oil-pump/distributor pulley i loosened the nut with everything atTDC and the old belt still on and tensioned,engine locked in gear.
Then i loosened the belt,swapped pulleys,re-tensioned old belt and tightened pulley-nut up.

I never do any thing with the engine at TDC, except when finally fitting the belt. If you work with the crank pulley 30 degrees before TDC, all the pistons are way down the bore, and you can rotate the cam, either accidently or deliberately at will, without any possibility of piston to valve contact.
When the cam and distributor positions are set, simply advance the crank to TDC and fit the new belt.
As said above, loosen and tighten the cam pulley bolt with the old belt in place.

Thanks guys.
Any tricks to removing the seal itself?

Cam seal fits in its own little mounting plate, which unbolts once the pully is off. Tap it out (and in) with a suitable size socket.