Do I need to wait after using E2 to move onto E3?

[Greenduck]

So I'm using E2, I'm about to get payed $40 for a day's worth of work out in the hot sun all day, which when mixed with the money I have, should be enough to afford E3. So since I'm so close to getting E3, I was wondering:

Is there some period of time I need to rest before I use E3? I'm using E2 right now. Can I just go straight into it? I'm hoping I can. Anyway, just figured I'd ask.

God job man! Don't know about the answer, sorry.