Hi, we'll stay at mongkok, which itinerary is correct : the peak then repulse bay or ? tq

Either can be ok. You will see from the approaches to the two destinations:
To the peak: It is suggested to take Tsuen Wan Line at Mong Kok Station to Central, from which walk to Garden Road to take the peak tram to the attraction;

To Repulse Bay: Take Tsuen Wan line to Central, where find bus no. 6, 6A, 6X, or 66 to your destination.

Therefore, you can visit either of them first.