250mA for about 12 hours would be fine. I personally would feel the packs periodically to check for excessive heat build-up - especially during the last couple hours.
250mA for around 10 hours followed by 5-7 hrs at 100mA would be fine too.
If you go the 100mA route you'll want to leave them on charge for at least 24 hrs. This rate may adequately charge the packs but, being half of C/10 (C/20), the results may be unpredictable for a 'first charge'.

If you can, cycle them a few times before committing them to use.