I know that small of a lamictal increase would probably be a very subtle improvement over a week or two, maybe getting another bit o' improvement for about a month after the increase. Lamictal did nothing for me until 200mg though.

They say therapeutic dose and generally starting dose for Prestiq is 50mg. Generally antidepressants take a couple weeks to kick in. It has a short half-life so I wouldn't think starting at 25mg would drastically shorten that despite having some in your system already.

I'd give it at least two weeks before expecting any noticeable improvement and a month maybe two before seeing if you get where you want to be with depression symptoms/mood instability/probably anxiety (not approved for that, but Effexor is and they're almost the same thing. Prestiq is I believe used off label because of this and the fact it has less side effects than Effexor).