Point of view of this article: press gas pedal before starting. This is only used in special cases. The advantage is that, as subject said, it can improve power and startup speed. However, this operation is more common. to damage clutch, it is not necessary to do this while driving.
First step on accelerator before starting to rev engine. At this time, engine speed has not dropped after releasing clutch, so transmission may produce a hard acceleration and start effect, and then continue to use accelerator pedals. Starting speed and power can be maintained. This operation is usually used in special situations such as emergency situations or competitions. It is not normally used as it can seriously damage clutch. The gear impact is also relatively large and therefore not recommended for frequent use.
Secondly, some older models do not have synchronizers on transmission gears, so when starting off or driving, you must press accelerator pedal before shifting gears to increase engine speed. gears on input shaft of gearbox, which can improve degree of engagement of input shaft gear and the output shaft gear so that it is smoother and less likely to cause stall when shifting into gear. However, manual transmissions produced today are already equipped with synchronizers, so this operation is not required.
I hope my answer helps you.
The above is just my personal opinion, feel free to comment/subscribe/like/.