hence (adv.)

Old English her "in this place, where one puts himself; at this time, toward this place," from Proto-Germanic pronominal stem *hi- (from PIE *ki- "this;" see he) + adverbial suffix -r. Cognate with Old Saxon her, Old Norse, Gothic her, Swedish här, Middle Dutch, Dutch hier, Old High German hiar, German hier.

As the answer to a call, in Old English. Right here "on the spot" is from c. 1200. Here and there "in various places" is from c. 1300. Phrase here today and gone tomorrow first recorded 1680s in writings of Aphra Behn. Here's to _____ as a toast is from 1590s, probably short for here's health to _____. Emphatic this here (adv.) is attested from mid-15c.; colloquially, this here as an adjective is attested from 1762. To be neither here nor there "of no consequence" is attested from 1580s. Here we go again as a sort of verbal rolling of the eyes is attested from 1950.

As a noun, "this place, the present" from c. 1600. Noun phrase here-and-now "this present life" is from 1829.

"two times, on two occasions, in two instances," late Old English twies, from Old English twiga, twigea "two times," from Proto-Germanic *twiyes (source also of Old Frisian twia, Old Saxon tuuio), from PIE *dwis-, adverbial form of root *dwo- "two." Spelling with -ce reflects the voiceless pronunciation.

Life is as tedious as a twice-told tale

Vexing the dull ear of a drowsy man.

["King John," III.iv.]

Think twice, then speak was an "old Prouerbe" by 1623. At twice, though less common than at once, means "at two distinct times; by two distinct operations."