All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
According to the authentic Sunnah, a Muslim is enjoined to be hospitable to guests. It was narrated on the authority of Abu Hurayrah that the Prophet, sallallaahu ‘alayhi wa sallam, said: "He who believes in Allaah and the Last Day, let him be hospitable to his guest." [Al-Bukhari and Muslim]
Another version of the Hadeeth reads, "He who believes in Allaah and the Last Day, let him entertain his guest generously.” [Abu Ya‘la - Shaykh Husayn Asad said that this Hadeeth has an authentic chain of narrators]
Among the good conduct associated with hospitality is to hasten to entertain the guest. Ibn Katheer commented on the story of Prophet Ibraaheem (Abraham) and the angels who visited him in Soorah 51 of the Quran, saying, “This verse [51:27] incorporates many aspects of the Islamic conduct of hosting guests…. He discretely brought the food and he did this very quickly while they were unaware that it was being prepared for them. He did not mention this favor to them by saying, "We will make food for you." Rather, he discretely had it prepared and placed it before them. He prepared the best kind of food he had, a young, fat roasted calf. He did not place the food far from them and invite them to come close to it to eat. Rather, he placed it right before them and did not order them to eat. Instead he invited them using a polite, kind and subtle invitation; the verse reads (what means): {And placed it near them; he said, "Will you not eat?"}"
The point is that the host should hasten to be hospitable to his guests; the delay of some guests may cause inconvenience to other guests who come on time. This is of course if it was not better to delay the dinner for a while so that the guests sit together and chat before serving the food. This is left to be decided according to the common practice in the community, because custom determines, i.e. customary law is authoritative in judgment in the absence of relevant Islamic texts. The host should also take into consideration whether those late guests are always late as a habit or whether this only happens occasionally.
Allaah Knows best.