I have always grown photoperiodics outdoors and I’ve always done three cycles: first plants planted in late March, the second in mid-April and the lasts in early May and they always grew very well. Don't trust the growshop guy, this is the best time to plant outdoors, they don't need extra light if they can get sun all day and portugal has a fantastic weather (very similar to mine).
Until the days begin to shorten your plants will continue to grow, so don't worry.