I do not understand why team managers did not set an exact date for starting SALE 1 stage. I do not see or posible dont understand, if there is no exact reason for which there is a deadline in the smart contract on January 20, and SALE 1 does not have the start date. Without understanding the logic of such a setting, I can think of anything about their ability to manage such a project.
If in the smart contract there is a deadline of January 20, I think setting the token distribution period in ICO must be set as the time period, so that it is possible to raise the necessary funds. If pre-sale sells only 2,500,000 tokens at the best price, then you can sell 13,500,000 by January 20 at a higher price, it must begin immediately after the pre-sales period. It is unlikely that you sell 13,500,000 tokens in an undetermined start-up period, but after December 27 in the context in which smart-contract January 20 is the deadline. Otherwise I appreciate the idea of the project and sincerely I wish very successful.
I admit honestly, I do not understand the problem you described. I will try to explain it, as I understood. I apologize if my answer is not satisfactory for you.
PRE-SALE is part of ICO. It will last from 20 to 27 December. It is likely that it will last shorter. If we sell 2,500,000 tokens - the pre-sale will end. The ICO runs from December 27 (then we start selling SALE I).
All dates are specified

If you have any questions, I am at your disposal.
My understanding was at 2 your anterior posts, where you tell me this "Only the pre-sale has a specific duration." Just read and will understand about this. My misunderstanding was about a specific duration as a period of every SALE period as you defined SALE 1, 2, 3. How you will be measure when you finish SALE 1 as a periode in situation when you will not sell the target nr. of tokens. For me corect is to set every SALE periode with specific duration, for example one week, or few days, etc.