It might be thought highly unusual, but there is nothing to stop a kartha, the gruhasthan, from splitting the performance of his son's upanayanam into four distinct sections, each with its own time-frame, its own anughnyai, etc.
It has been noted elsewhere in these columns that there are no less than 40 ghattams, from first anughnyai to final haaraththy.
Presumably, the invitation will tell Brahmana guests to be present at the celebration venue early on 2 July 2017 morning for Stage One of the upanayanam ceremony when the kartha and his pathni will receive the formal anughnyai of the assembled Brahmana Parishad to the accompaniment of the manthram "ruthyaasma havyair namasopasadya......" and the kartha will be presented with the darbha pavithram. The kartha will then present dakshanai to the Parishad with the manthram "asheshe he parishad, bhavath paada moole maya samarppithaam imaam sauvarneem dakshinaam....."
The shaasthrigals will then proceed through the first few ghattams, including udakashaanthi and naandee shobhana shraaddham, and stop for lunch, having completed Stage One. The other Brahmanas will also presumably be served lunch.
The shaasthrigals will start Stage Two in the evening of 2 July 2017,beginning with punyaahavaachanam and go on till ghattam no. 25 "guru upadesham". Then break for the day, have dinner, and go home. So will the Braahmana Parishad.
Presumably, Stage Three will start around 4.00 am on 3 July 2017 (it is still night of the previous day according to Hindu custom) with ghattam no.26 "upanayana sankalppam" by the kartha and his pathni. And go on till ghattam no. 30 "brahmopadesham" at 5.30 am (still night) and ending with ghattam no. 37 palasha homam". The shaasthrigals and guests will then go home again.
At Stage Four at around 11.30 am on 3 July 2017, shaastghrigals and guests will return, for "guru dakshinai", "aasheervaatham", "haarathy", and "Braahmana bhojanam" to all guests and to shasthrigals.
Notable is the fact that during the major part of the proceedings, i.e. the whole of Sunday 2 July 2017, the thithi is navami, an inauspicipus thithi for starting and performing upanayanam. The ceremony would have been begun in this thithi, with the anugnyai of the assembled Braahmana Parishad.
Moreover, the vadu will still not be able to perform his maadhyaahnikam and his soorya-darishanam immediately after his brahmopadesham, as is the custom. He will have to wait till noon, i.e. Stage Four, when the shaasthrigals return after performing another ritual elsewhere. Neither will the kartha or the shaasthrigals be able to do this (maadhyaahnikam and soorya darishanam). All of them can of course do the praatha sandhya-vandanam at the correct time (around 6.00 am), if they wish.
Again, highly unusual, but probably nothing to stop the kartha and the shaasthrigals if they so wish.
The core of the whole samskaaram is of course the "brahmopadesham". Having this done at night, i.e. 5.30 am, is wrong and ineffective. Might as well do homam on an unlit fire or on ashes of a previous fire.
The whole of the essential sandhya-vandanam routine, whether praatha, sandhya, or maadhyaahnikam, is worshipping the Sun as it rises, sets, or stands overhead at high noon. Doing sandhya after sunset or before sunrise is totally wrong, is a null act, and will bring no good to the vadu or his parents (or the erring shaasthrigals).
S Narayanaswamy Iyer