Sparkling Growth Process

A sparkling and a protoform both have a limited amount of sentio metallico that are present in their bodies, and that sentio metallico is what triggers the rush of growth materials stored in their body for growth spurts. When the sentio metallico store is depleted, the sparkling/protoform will not have any more major growth spurts, their body doing fine adjustments according to their coding using repair nanites.
Nutrients from energon gets stored in storage chambers in certain parts of the body, and when those chambers are full the sparkling will undergo a growth spurt.
there is very gradul growth in a sparklings life, but they dont noticeably grow over time like an organic. more a very small amount of self repair that subtely tweaks the length of a strut, or base protoform expanding, causing plating to have to be shifted.
they go through various amounts of growth spurts, where over the course of a few days for sparklings, or overnight for protoforms their body releases the stored minerals, sentio metallico, and unassigned nanites. These materials go into the auto-repair system, and following the hidden base coding that predicts how the sparkling or protoform will appear when matured, adjusts sections of the body. Everything gets covered very generally, no body part being vastly out of proportion, a quality that sticks with both protoforms and sparklings as a survival mechanism. If the protoform cannot escape a situation due to unbalanced limbs, it will die.
These few days are normally spent not doing a lot, as extended stress will distort weakened areas that are being rebuilt by repair nanites. These growth spurts will lengthen struts, add plating, among other things. The process happens much quicker in protoforms due to their processors running on instinct instead of actively learning, and is also another survival mechanism. Sparklings are more likely to be nurtured through this time, and therefore the growth spurts are more likely to take longer.
A growth spurt also applies to the t-cog, or in the absence of one,the transformation sequences in their processor. This allows the new materials to be made internally and the use of transformation sequences to shift new plating or pieces of struts to their proper place. This can result in sudden twitches, movements, or rippling plating, among other side effects. In a protoform, the sequences can get so intense as it is a much shorter process, that the protoform usually has to hide for a day or two as it is extremely vulnerable while these pieces are shifting.
Growth spurts are most often described as a drawn out mass displacement transformation, except you cant go back.
A sparkling can be taken to a medic to activate a growth spurt early using supplied nanites and minerals, but doing so if the sparklings processor hasnt matured to a certain point, it is considered traumatizing and cruel. However, this process can be used in even of a delayed growth spurt, or customisation of plating