Doing research on ESTA / J-1 visa

Context: I am a researcher from an ESTA eligible country. I have a planned research stay coming up in 2019 (April - July), where I would work on a project under a J-1 Visa (with US funding).
Now my home university (my current employer) has suggested to send me to the same place on their funds "to facilitate and explore research collaborations" from January to March. Basically I would travel to the US (reimbursed and paid by my home university) before the actual visit - from January to mid-March, return for about 2 weeks and then start my J-1 visa in April.
As January is coming up quickly, I would like to do the first part on ESTA, as it is basically a business trip without US funding (?!?). But is that allowed, or would it jeopardize my J-1 to do this almost back-to-back? Would I need to get another J-1 visum?
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Do I need ESTA if I have J-1 visa?
Individuals traveling on valid visas are not required to apply for ESTA.How easy is it to get a J-1 visa waiver?
The no-objection statement is typically the easiest way to get a J-1 visa waiver. This type of waiver simply says that your government doesn't object to your remaining in the United States.How early can you enter the US on a J-1 visa?
Step 5: Travel to the US Once you have obtained your J-1 visa, you are ready to travel to the U.S. Immigration regulations allow you to enter the U.S. no earlier than 30 days prior to the start date of your program indicated in Section 3 of your SEVIS Form DS-2019.How long can you stay in US with J-1 visa?
Length of Time Business and Industrial Trainees Can Stay in the U.S. on a J-1 Visa. Business and industrial trainees may be issued J-1 visas for a maximum of 18 months.Short Term Scholar \u0026 Research Scholar USA Explained || J-1 Visa Consulting
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Tima Miroshnichenko, Mikhail Nilov, Mikhail Nilov, Mikhail Nilov