First, with the 1/2 wave cables still connected, tune the cavity with the tuning-rod as accurate as possible, to minimal VSWR at the pass-frequency. The fine-tuning bolt should stay abt. 3 turns in, to allow easy finetuning afterwards, when the filter is completed.
Remove the testcables.
Shorten the "cold" sides of the links down to topplate "A". Bend and shorten the the hot side of one link to the BNC connector in the side of the cavity. Solder it, while a dummy-plug is in the recepticle for positioning the centre-pin. Shorten the "hot" side of the other link low to the topplate. Solder a 1/4 wave (notch-frequency) 50 ohms teflon cable to the out going link. It will later be connected to the next cavity.