Leaders of the rich northeastern region are locked in a tense standoff with Spain's central government over the vote.
Spain's conservative government says the referendum is unconstitutional and the country's Constitutional Court has suspended it while it deliberates on its legality, a process that could take years.
Asked during an interview with Catalan radio Rac1 after which date it would become impossible for the Catalan government to properly prepare the referendum, Catalan government spokesman Francesc Homs said: "Around October 13th, 14th or 15th."
"You can extend some of the timeframes... but we can't decide to do this, if it is something we must decide, on November 7th or 8th," he added.
The comments from the regional government's spokesperson also highlight growing divisions within the pro-independence movement in Catalonia, with the ERC party warning such talk on the part of the government could kill off the vote.
Only two Catalans in 10, or just 23 percent, wanted Catalonia's president Artur Mas to "ignore" the court ruling and forge ahead with the referendum, according to a poll published Sunday in the centre-left national newspaper El Pais.
Forty-five percent wanted Mas to "comply with the legal decision" and negotiate to find a means to hold a vote which would "respect the constitution", while 25 percent wanted regional leaders to find an alternative solution that favoured independence but did not require holding a vote.
The survey also showed that nearly half of those polled would opt for Catalonia to remain part of Spain if it were granted special status, while only 29 percent wanted full independence outright.
Catalan pro-independence parties declared Friday they were "united" on their referendum bid, which threatens to trigger Spain's biggest constitutional crisis in decades.
Proud of their distinct language and culture, many of the 7.5 million inhabitants in the prosperous region have long complained they get a raw deal from the government in Madrid, which decides how their taxes are spent.
They have been fired up by last month's independence referendum in Scotland, even though voters there rejected a separation from Britain.