Hi & welcome to TAS
What I've found (generally) is that the rolls are fine from weaning age, so at 4 months they should manage them fine (it's just the same food but in a bigger size). Even my wee Kune Kunes manage the rolls from around 4 weeks, so at 4 months yours will be fine. This is assuming it's sow & weaner rolls. I'm not certain of protien levels in sow rolls - it varies from brand to brand and some are designed for 'dry' sows (which have lower levels of protien) if it's gilts for breeding with that you have, try to keep their protien levels at around 18% to ensure good growth and breeding potential. If you check the label on your feed bags you'll see the breakdown for protein etc
HTH
Karen