My experience (yours may differ) is that the increase in capacity achieved by cycling a new pack is insignificant. I replaced NiCd packs on four planes this spring. I cycled each new pack several times using a C/10 charger before I put it in its plane. These were 700 mAh Sanyo AA cell packs. The change in capacity from first cycle to last was less than 30 mAh.
I did the same with some Duracell 2700 mAh NiMH loose cells that I use for my bicycle lights and also with some Eneloop 2000 mAh cells. Again, the capacity change was not worth worrying about, maybe 100 mAh.

I suspect the 'conditioning cycles' are more important if you are going to use a peak detect charger. Then conditioning the cells with several long C/10 charges may be important. But the OP is presumably using a C/10 wall wart.

The only danger with discharging into a load is the possibility of driving the weakest cell into reverse charge. That is said to be damaging to the cell. This is the reason to stop the discharge at 1V per cell, i.e. 4.0 V for a 4-cell pack.

Anyway, I don't think the OP will be able to discharge into a load through his charge jack unless the diode has been shorted. There are lots of old posts on this, search on "transmitter diode".