The former Paris St Germain boss is also "totally aware" but not scared of Chelsea's ruthless streak when it comes to sacking managers.
Tuchel has become the 15th managerial appointment of the Roman Abramovich era, overseeing his first match in Wednesday's goalless Premier League draw with Wolves.
Tuchel's concession on the immediate turnaround demanded by the Blues board is at odds with his predecessor Frank Lampard, who had wanted time for an extended Stamford Bridge rebuild.
Chelsea's new manager believes such luxuries do not exist in west London, insisting he is comfortable with the loftiest of expectations.
Asked when Chelsea – who are currently 11 points behind Premier League leaders Manchester City having also played a game more – will be ready to win the league, the 47-year-old German replied: "Honestly, we have to be ready when the new season starts.
"We have to be ready to compete. Chelsea is a club where you compete for trophies and there is no time to waste.
"As a manager there is no time to waste.
"Honestly now we compete for the FA Cup, and we will get ready absolutely to compete at the highest level in the Champions League.
"And we want to create a team that is confident enough to beat anybody in two games.
"And from latest the start of next season we want to be ready to close the gap to Manchester City and Liverpool."
Asked if he is concerned about Chelsea's reputation for sacking managers, Tuchel said: "Yes and no, but I'm absolutely grateful I can work on this level.
"If you sign for Chelsea you sign for the hunger of titles, you sign for being absolutely competitive in every competition you play. I'm totally aware of that.
"It is like you said but it does not scare me, we have big ambitions, and me myself I have the biggest ambitions.
"I'm very excited about the mixture of the team, I'm very excited about the structure of the club, and the first days were amazing.
"And I'm absolutely aware that at some point everybody expects results but honestly, I'm doing that of myself."
Chelsea's all-time record goalscorer, Lampard's status as a Stamford Bridge cult hero had no bearing in his managerial reign.
The 42-year-old wound up with just 18 months at the helm, and was sacked less than six months after overseeing a £220million squad overhaul last summer.
Tuchel paid tribute to Lampard, in hoping that the club's fan base will throw their support behind him now he is at the tiller.
"A fan backlash? I don't know, I hope not because that would be hard on the team," said Tuchel.
"Because we need our supporters like any team, and in a stadium like ours, like Chelsea, to have the fans so close and so close behind the team makes is absolutely the difference.
"I can absolutely assume it's a big, big disappointment for the fan base to see that Frank was sacked.
"I can only repeat I have the biggest respect. I was a huge fan of Frank as a player, it was a huge joy to watch him play and to see how he played.
"He was one of the key figures to demonstrate in 90 minutes what Chelsea was about: intensity, devotion, winning mentality.
"And so I have the biggest respect for him personally and for his legacy.
"It just got bigger when I received a personal message today to wish me all the best and maybe to meet in the future when this is possible.
"So honestly nothing has changed there.
"But in the last 72 hours the club made clear to me this is clearly not my fault and I cannot change the situation for him.
"The decision was made and I was handed the opportunity, but I totally mean what I say about Frank."