Fleas and frontline question...

Kermie has never had a problem with fleas. We have had her on Frontline and our apartment gets sprayed so no problem. We went and stayed with my in-laws last weekend and they admitted they have had an issue with fleas. When we got home I gave Kermie a bath but I have noticed she has been scratching a lot more lately. I have seen a few on her but she HATES for me to look and won't sit still long enough for me to get them. Anyways, she is due for her next Frontline treatment on Sunday. Is there any benefit or harm it giving it early? I know it is just a few days but I want to make sure and I want to nip these fleas in the bud!