I think I've answered my own question by doing a little reading on the USPTO website that I should have done before posting the original question.

Because I, as an individual, would be considered a "related company" to SuperGreat LLC, it is my understanding that as long as I am using the goods in interstate commerce, it is okay to list the date of first use in commerce as February 1st, even if SuperGreat LLC wasn't officially formed on that date.
However, I would appreciate confirmation that my thinking is on the right track, if possible.
I base my thinking on the following exerpts of code:
1201.03 Use by Related Companies
Section 5 of the Trademark Act, 15 U.S.C. §1055, states, in part, as follows:
Where a registered mark or a mark sought to be registered is or may be used legitimately by related companies, such use shall inure to the benefit of the registrant or applicant for registration, and such use shall not affect the validity of such mark or of its registration, provided such mark is not used in such manner as to deceive the public.
Section 45 of the Act, 15 U.S.C. §1127, defines “related company” as follows:
The term “related company” means any person whose use of a mark is controlled by the owner of the mark with respect to the nature and quality of the goods or services on or in connection with which the mark is used.
Thus, §5 of the Act permits applicants for registration to rely on use of the mark by related companies. Either a natural person or a juristic person may be a related company. 15 U.S.C. §1127.
The essence of related-company use is the control exercised over the nature and quality of the goods or services on or in connection with which the mark is used. When a mark is used by a related company, use of the mark inures to the benefit of the party who controls the nature and quality of the goods or services. This party is the owner of the mark and, therefore, the only party who may apply to register the mark. Smith International, Inc. v. Olin Corp., 209 USPQ 1033, 1044 (TTAB 1981).
Reliance on related-company use requires, inter alia, that the related company use the mark in connection with the same goods or services recited in the application. In re Admark, Inc., 214 USPQ 302 (TTAB 1982) (related company use not at issue where the applicant sought registration of a mark for advertising agency services and the purported related company used the mark for retail store services).
A related company is different from a successor in interest who is in privity with the predecessor in interest for purposes of determining the right to register. Wells Cargo, Inc. v. Wells Cargo, Inc., 197 USPQ 569 (TTAB 1977), aff’d, 606 F.2d 961, 203 USPQ 564 (C.C.P.A. 1979).
See TMEP §1201.03(c) regarding wholly owned related companies, §1201.03(d) regarding corporations with common stockholders, directors or officers, §1201.03(e) regarding sister corporations, and §1201.03(f) regarding license and franchise situations.
But, it seems clear that I have to declare this on the application.
1201.03(a) Use Solely by Related Company Must be Disclosed
If the mark is not being used by the applicant but is being used by one or more related companies whose use inures to the benefit of the applicant under §5 of the Act, then these facts must be disclosed in the application. 37 C.F.R. §2.38(b). See Pease Woodwork Co., Inc. v. Ready Hung Door Co., Inc., 103 USPQ 240 (Comm’r Pats. 1954); Industrial Abrasives, Inc. v. Strong, 101 USPQ 420 (Comm’r Pats. 1954). Use that inures to the applicant’s benefit is a proper and sufficient support for an application and satisfies the requirement of 37 C.F.R. §2.33(b)(1) that a §1(a) application specify that the applicant has adopted and is using the mark.
The party who controls the nature and quality of the goods or services on or in connection with which the mark is used should be set forth as the applicant. In an application under §1(a) of the Trademark Act, the applicant should state in the body of the application that the applicant has adopted and is using the mark through its related company (or equivalent explanatory wording). In a §1(b) application, the statement that the applicant is using the mark through a related company should be included in the amendment to allege use under 15 U.S.C. §1051(c) (see TMEP §§1104 et seq.) or statement of use under 15 U.S.C. §1051(d) (see TMEP §§1109 et seq.).
The applicant is not required to give the name of the related-company user, unless it is necessary to explain information in the record that clearly contradicts the applicant’s verified claim of ownership of the mark.
The applicant may claim the benefit of use by a related company in an amendment to the application. Greyhound Corp. v. Armour Life Insurance Co., 214 USPQ 473, 475 (TTAB 1982).
If the applicant and a related company both use the mark, and it is the applicant’s own use of the mark that is relied on in the application, then the applicant does not have to include a reference to use by a related company in the application. See TMEP §1201.05.
For anyone who knows more about this than me (which would probably be almost any of you reading this), am I on the right track in thinking that I could use the earlier date for first used in commerce, even if it predates the existence of SuperGreat LLC as long as I disclose this in the TM application?