頭先=just a short while ago;a moment ago;just now,
e.g:頭先妳条仔打電話俾妳（Your boyfriend called you just a moment ago.）
*maybe more than 5 minutes
啱啱=only just.just now
e.g:你點解唔嚟早一步，姖啱啱走咗！(why didn't you come earlier, she only just leave.)
*maybe less than 5 minutes
=only; just 恰恰好
e.g: 呢隻火雞啲火候啱啱好。 the duration of the turkey is just ok.
e.g: 啱啱够時間赶上班機。Just made the plane./We're just in time to catch the plane.
just my opinion, actually, in our daily life, we are not very clear to distinguish the differece between them.
