Alternative phrase/word for 'Up to this point'

Previously, Rosemary’s ‘maternal instinct’ had remained dormant.

Existing or occurring before something else in time or order; prior

TFD

Or 'until now'

'Heretofore' should fit the bill

Hitherto, Rosemary’s ‘maternal instinct’ had remained dormant.

ODO:

hitherto
ADVERB
Until now or until the point in time under discussion.

‘He was billeted at her home where her seven brothers had hitherto protected her from any approach by potential suitors.’

In your case, I would opt for so far, until then, or prior to that time.

For more variety, I recommend you the following list of synonyms in WorldHippo:

up to the present moment, hitherto, so far, thus far, till now, to date, as yet, until now, until today, up to now, as of now, up to the present time, yet, thitherto, till then, until then, up to then, up to the present, up to that point, heretofore, up until then, up until now, till the present, up till now, by this time, until the present, theretofore, previously, up to this time, still, formerly, already, before, earlier, even now, before this, since, beforehand, earlier on, prior to now, prior to this time, prior to the present time, until this time, before now, by now.