Would need to do testing, but I'm pretty sure awakening just increases the growth rates (as in, it doesn't give a flat stats boost). The stat increases you see from awakening are the growth rates being retroactively applied to the ninja.

I did some quick testing because I was curious. The amount of stats you gain each level up is your growth rate divided by 100, and is affected by your ninja's star level. So if you had an HP growth rate of 1000 on a 3 star ninja, you would gain 11 HP per level (1000 / 100 * 1.1). If you awaken someone, it just adjusts the growth rates and your ninja has the stats that it should have based on it's level and new rates.

Not sure if mood affects this, but it probably does.

EDIT, pictures:
Level 1 HP -> Level 30 HP (Green Awakening)
2982 + (1204 / 100 * 1.1) * 29 = 3366

Level 1 HP -> Level 30 HP (Blue Awakening)
2982 + (1264 / 100 * 1.1) * 29 = 3385

This post was last edited by cra***@gmail.com at 2017-5-5 14:24

One more part to show that what level you awaken doesn't matter. I leveled Karin from 30 to 70 first and then at 70 awakened her from blue to purple. You can see that her health adjusts based on the new growth rate:

Level 1 HP -> Level 70 HP (Purple Awakening)
2982 + (1505 / 100 * 1.1) * 69 = 4124

There's a very slight difference, but that is likely due to the increased growth rates also affecting the base stats, which we have no way to see since we can't awaken level 1 characters. If she had been stuck wwith the blue awakening value for health gained when leveling, she would have:

Level 1 HP -> Level 70 HP (Blue Awakening)
2982 + (1264 / 100 * 1.1) * 69 = 3941


which is clearly not the case.

TL;DR: it doesn't matter when you awaken a character, you won't lose any stats