LUMP SUM VS WAIT- Roth IRA

I didn't invest my Roth IRA contributions this year, obviously kicking myself so no need for outside pressure, but currently looking into VTI, VOO, QQQM and other ETFs. From this post you can tell I am in need of a set it and forget it strategy. 30 years old $8k cash in account from this year and some of last year. However, it looks like markets are kind of up right now, does it make sense to lump sum into some of these accounts now or is there usually a spring lull? Or should I just do a little bit at a time over the next few months to consider this? Thanks.