If you do not have vertical guidance (and most light twins do not), or somebody to calculate for you the descend rate
You don't need vertical guidance at least not in an instrument.
Some tricks that make this easy:
You don't want to reach MDA and the MAP at the same time, that's obvious.
The MAP is NOT the last point from which a normal descent to landing can be made. So what if we reach MDA one minute prior to reaching the MAP?
9 NM = 6 minutes @ 90 KTS = 5 minutes to descent
7.5 NM = 5 minutes = 4 minutes to descent
6 = 4-1=3
4.5 = 3-1=2
3 = 2 -1 =1 minute to descent to MDA
Youll need at least DME for this but it also works (less accurate) if ATC provides you with the distance on the approach clearance.
Let's assume that we are 6 NM from the MAP. That is 4 minutes at 90 kts.
Which means 3 minutes to descend. If we have 1800' to go that's 600fpm.
1500' remaining is 500 fpm.
To calculate the VDP the quick and dirty way: 3 x MDH
So if MDH is 500 AGL then VDP is 3 X 500 = 1500 = 1.5NM
If MDH is 750 the VDP is 2.2 NM
From the VDP it's a 3 degree descent to the runway.
So yes, it does depend a little on what equipment you have.
But I would use these tricks in a C152 with only VOR and no DME.
Full VOR approach, 4 minutes outbound, procedure turn; 3 minutes to descent on the inbound. If the winds are not too strong it works amazingly accurate.