I am trying to better understand how VFPL works on my AF-5600 to be able to arrive at a pattern (or other) altitude using a reasonable rate of descent.

It looks like the simplest way to use VFPL is by having crossing altitudes set for all waypoints in which case one takes off with the plane in VFPL mode and as long as the destination has a BOD defined (say, 2 miles away to cross at TPA), the EFIS will manage the descent profile appropriately. The catch that I see in this is that one has to define a TOC.

My normal procedure after takeoff would be to climb to cruise altitude as quickly as possible (unless there are airspace restrictions like an overlying Class B/C or if I need to manage CHTs) so I usually do not have any TOC location. In this scenario (with a very simple direct route from the origin to destination airports), the AP is set to ALT mode with the ALT bug set to the cruise altitude (obviously, VFPL has been off so far). Once I am at cruise altitude, if I set a BOD and turn on VFPL mode in the AP (the ALT bug is still set to my cruise altitude), would it then start automatically descending at the TOD or would I get a cue that I need to change the ALT bug to the target crossing altitude so that the EFIS can direct the AP to start a descent?

Or, do I need to create an additional waypoint ( between my current cruise altitude location and the TOD) with a crossing altitude to be my current cruise altitude, switch the AP to VFPL mode (which shouldn't do anything right away because I will already be at that altitude) at which point it will then be in VFPL mode and will initiate a descent at the correct TOD?

I guess this is a long-winded way of asking how I can switch to VFPL mode to appropriately start the descent after using the ALT mode as usual to get up to cruise altitude (without having to come up with a TOC and crossing altitudes for any intermediate waypoints).

A related question is how does the ALT bug function when the EFIS is in VFPL mode?

Thanks,

Vas