Although Everton have agreed a deal with Southampton and terms with Koeman, practical issues over finalising contracts are said to have arisen due to the 53-year-old being away on a second pre-planned holiday.
According to local press – both Everton and Koeman are prepared to wait until he returns on Monday.
Koeman’s brother, Erwin, will join Everton as assistant manager and the pair will be joined by Jan Kluitenberg, who takes up the role of assistant first team coach/physical coach. Kluitenberg worked with Koeman at Vitesse Arnhem, Benfica, AZ Alkmaar, Feyenoord and Southampton.
Koeman’s honours as a player include winning the 1988 European Championship with the Dutch national team, the European Cup – now the Champions League – with PSV Eindhoven in 1988 and Barcelona in 1992 as well as domestic league titles in the Netherlands and Spain.
He played 763 games for club and country, scoring 253 goals, including the winner for Barcelona against Sampdoria in the 1992 European Cup final at Wembley.
His managerial career has taken in spells at Vitesse, Ajax, Benfica, PSV, Valencia, AZ Alkmaar, Feyenoord, before he joined Southampton in June 2014.