'Single Line' number ports usually take place at circa 10.00 a.m. on the porting date.
'Multi Line' / other ports may take place at a similar time but as they are usually more complex and do not follow the largely automated procedure that applies to single line ports they are often allocated to afternoon slots at circa 3:00 p.m.
However, this is dependent upon the timely activity of the LCP (losing communications provider) to release the number at the allotted time; until that is done there is little the GCP (gaining communications provider) can do.
Unless specifically advised otherwise, please assume circa. 10.00 a.m. for 'Single Line' ports, circa. 3.00 p.m. for 'Multi Line' / other ports.