  High-cadence, multiwavelength observations have continuously revealed the
diversity of tidal disruption events (TDEs), thus greatly advancing our
knowledge and understanding of TDEs. In this work, we conducted an intensive
optical-UV and X-ray follow-up campaign of TDE AT2023lli, and found a
remarkable month-long bump in its UV/optical light curve nearly two months
prior to maximum brightness. The bump represents the longest separation time
from the main peak among known TDEs to date. The main UV/optical outburst
declines as $t^{-4.10}$, making it one of the fastest decaying optically
selected TDEs. Furthermore, we detected sporadic X-ray emission 30 days after
the UV/optical peak, accompanied by a reduction in the period of inactivity. It
is proposed that the UV/optical bump could be caused by the self-intersection
of the stream debris, whereas the primary peak is generated by the reprocessed
emission of the accretion process. In addition, our results suggest that
episodic X-ray radiation during the initial phase of decline may be due to the
patched obscurer surrounding the accretion disk, a phenomenon associated with
the inhomogeneous reprocessing process. The double TDE scenario, in which two
stars are disrupted in sequence, is also a possible explanation for producing
the observed early bump and main peak. We anticipate that the multicolor light
curves of TDEs, especially in the very early stages, and the underlying physics
can be better understood in the near future with the assistance of dedicated
surveys such as the deep high-cadence survey of the 2.5-meter Wide Field Survey
Telescope (WFST).
